definition of presentation in obg

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INTRODUCTION

Diagnosis and management of face and brow presentations will be reviewed here. Other cephalic malpresentations are discussed separately. (See "Occiput posterior position" and "Occiput transverse position" .)

Prevalence  —  Face and brow presentation are uncommon. Their prevalences compared with other types of malpresentations are shown below [ 1-9 ]:

● Occiput posterior – 1/19 deliveries

● Breech – 1/33 deliveries

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Obstetric Examination

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Original Author(s): Minesh Mistry Last updated: 12th November 2018 Revisions: 7

• 1 Introduction
• 2 Preparation
• 3 General Inspection
• 4 Abdominal Inspection
• 5.1 Fundal Height
• 5.3 Presentation
• 5.4 Liquor Volume
• 5.5 Engagement
• 6 Fetal Auscultation
• 7 Completing the Examination

The obstetric examination is a type of abdominal examination performed in pregnancy.

It is unique in the fact that the clinician is simultaneously trying to assess the health of two individuals – the mother and the fetus.

In this article, we shall look at how to perform an obstetric examination in an OSCE-style setting.

Introduction

• Introduce yourself to the patient
• Wash your hands
• Explain to the patient what the examination involves and why it is necessary
• Obtain verbal consent

Preparation

• In the UK, this is performed at the booking appointment, and is not routinely recommended at subsequent visits
• Patient should have an empty bladder
• Cover above and below where appropriate
• Ask the patient to lie in the supine position with the head of the bed raised to 15 degrees
• Prepare your equipment: measuring tape, pinnard stethoscope or doppler transducer, ultrasound gel

General Inspection

• General wellbeing – at ease or distressed by physical pain.
• Hands – palpate the radial pulse.
• Head and neck – melasma, conjunctival pallor, jaundice, oedema.
• Legs and feet – calf swelling, oedema and varicose veins.

Abdominal Inspection

In the obstetric examination, inspect the abdomen for:

• Distension compatible with pregnancy
• Fetal movement (>24 weeks)
• Surgical scars – previous Caesarean section, laproscopic port scars
• Skin changes indicative of pregnancy – linea nigra (dark vertical line from umbilicus to the pubis), striae gravidarum (‘stretch marks’), striae albicans (old, silvery-white striae)

Fig 1 – Skin changes in pregnancy. A) Linea nigra. B) Striae gravidarum and albicans.

Ask the patient to comment on any tenderness and observe her facial and verbal responses throughout. Note any guarding.

Fundal Height

• Use the medial edge of the left hand to press down at the xiphisternum, working downwards to locate the fundus.
• Measure from here to the pubic symphysis in both cm and inches. Turn the measuring tape so that the numbers face the abdomen (to avoid bias in your measurements).
• Uterus should be palpable after 12 weeks, near the umbilicus at 20 weeks and near the xiphisternum at 36 weeks (these measurements are often slightly different if the woman is tall or short).
• The distance should be similar to gestational age in weeks (+/- 2 cm).
• Facing the patient’s head, place hands on either side of the top of the uterus and gently apply pressure
• Move the hands and palpate down the abdomen
• One side will feel fuller and firmer – this is the back. Fetal limbs may be palpable on the opposing side

Fig 2 – Assessing fetal lie and presentation.

Presentation

• Palpate the lower uterus (below the umbilicus) to find the presenting part.
• Firm and round signifies cephalic, soft and/or non-round suggests breech. If breech presentation is suspected, the fetal head can be often be palpated in the upper uterus.
• Ballot head by pushing it gently from one side to the other.

Liquor Volume

• Palpate and ballot fluid to approximate volume to determine if there is oligohydraminos/polyhydramnios
• When assessing the lie, only feeling fetal parts on deep palpation suggests large amounts of fluid
• Fetal engagement refers to whether the presenting part has entered the bony pelvis
• Note how much of the head is palpable – if the entire head is palpable, the fetus is unengaged.
• Engagement is measured in 1/5s

Fig 3 – Assessing fetal engagement.

Fetal Auscultation

• Hand-held Doppler machine >16 weeks (trying before this gestation often leads to anxiety if the heart cannot be auscultated).
• Pinard stethoscope over the anterior shoulder >28 weeks
• Feel the mother’s pulse at the same time
• Should be 110-160bpm (>24 weeks)

Completing the Examination

• Palpate the ankles for oedema and test for hyperreflexia (pre-eclampsia)
• Thank the patient and allow them to dress in private
• Summarise findings
• Blood pressure
• Urine dipstick
• Hands - palpate the radial pulse.
• Skin changes indicative of pregnancy - linea nigra (dark vertical line from umbilicus to the pubis), striae gravidarum ('stretch marks'), striae albicans (old, silvery-white striae)
• One side will feel fuller and firmer - this is the back. Fetal limbs may be palpable on the opposing side

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Chapter 27:  Compound Presentations

George Tawagi

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Prolapse of hand and arm or foot and leg.

• MANAGEMENT OF COMPOUND PRESENTATIONS
• Full Chapter
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A presentation is compound when there is prolapse of one or more of the limbs along with the head or the breech, both entering the pelvis at the same time. Footling breech or shoulder presentations are not included in this group. Associated prolapse of the umbilical cord occurs in 15 to 20 percent of cases.

Easily detectable compound presentations occur probably once in 500 to 1000 confinements. It is impossible to establish the exact incidence because:

Spontaneous correction occurs frequently, and examination late in labor cannot provide the diagnosis

Minor degrees of prolapse are detected only by early and careful vaginal examination

Classification of Compound Presentation

Upper limb (arm–hand), one or both

Lower limb (leg–foot), one or both

Arm and leg together

Breech presentation with prolapse of the hand or arm

By far the most frequent combination is that of the head with the hand ( Fig. 27-1 ) or arm. In contrast, the head–foot and breech–arm groups are uncommon, about equally so. Prolapse of both hand and foot alongside the head is rare. All combinations may be complicated by prolapse of the umbilical cord, which then becomes the major problem.

FIGURE 27-1.

Compound presentation: head and hand.

The etiology of compound presentation includes all conditions that prevent complete filling and occlusion of the pelvic inlet by the presenting part. The most common causal factor is prematurity. Others include high presenting part with ruptured membranes, polyhydramnios, multiparity, a contracted pelvis, pelvic masses, and twins. It is also more common with inductions of labor involving floating presenting parts. Another predisposing factor is external cephalic version. During the process of external version, a fetal limb (commonly the hand–arm, but occasionally the foot) can become “trapped” before the fetal head and thus become the presenting part when labor ensues.

Diagnosis is made by vaginal examination, and in many cases, the condition is not noted until labor is well advanced and the cervix is fully dilated.

The condition is suspected when:

There is delay of progress in the active phase of labor

Engagement fails to occur

The fetal head remains high and deviated from the midline during labor, especially after the membranes rupture

In the absence of complications and with conservative management, the results should be no worse than with other presentations.

Mechanism of Labor

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Emergency Obstetrics and Pediatrics

2-02. definitions — common obstetric terms.

a. Abortion — the termination of pregnancy before the fetus reaches the stage of viability which is usually less than 21 to 22 weeks gestation (or less than 600 gm in weight).

b. Afterbirth — placenta, membrane, and umbilical cord which are expelled after the infant is delivered.

c. After pains — pain due to contractions of the uterus after the placenta has been expelled, following childbirth.

d. Amniotic fluid — approximately one liter of fluid in a sac which surrounds the fetus. This fluid protects and cushions the fetus during its development.

e. Amniotic sac (bag of waters) — thin bag which totally encloses the fetus during the development in the uterus.

f. Amniotomy — artificial rupture of the amniotic sac membranes; also, a method of inducing contractions.

g. Analgesic — medication which lessens the normal perception of pain.

h. Anesthesia — medication that causes partial or total loss of sensation with or without loss of consciousness.

i. Apgar scoring — rating system for newborn babies, measuring the baby’s general condition on a scale from 1 to 10.

j. Bloody show — small amount of blood-tinged discharge due to rupture of small capillaries in the cervix.

k. Breech — birth with baby’s buttocks or feet coming first.

l. Catherization — emptying the bladder by insertion of a small pliable tube through the urethra.

m. C-section (cesarean section) — delivery of the baby and the placenta through an incision made into the abdominal wall of the uterus.

n. Cephalic delivery — in normal circumstances, presentation of the head first.

o. Cervix — neck of the uterus; “mouth of the womb” which dilates and effaces during labor (dilates to 10 centimeters to accommodate the head of the baby passing through the cervix during the birth process).

p. Colostrum — thin, yellowish fluid preceding breast milk; usually present by the second day after the birth of the baby. Sugar content of this fluid is the same as breast milk. Colostrum contains as much or more protein material and salts as breast milk but less fat. Colostrum carries protective antibodies.

q. Contractions — also called labor, the term contractions refers to the muscles of the uterus contracting rhythmically and forcefully just before birth. Terms associated with contractions are as follows:

(1) Intensity — strength of the muscle contractions.

(2) Duration — length of time from start to end of the contraction.

(3) Frequency — time from the beginning of one contraction to the beginning of the next contraction.

(4) Braxton Hicks contractions — also called false labor, this refers to irregular uterine contractions occurring after the 28th week of pregnancy; felt mainly in the abdomen; changes in the woman’s activity will usually cause these contractions to go away.

r. Crowning — appearance of the baby’s head at the vaginal opening.

s. Dilation (or dilatation) — opening of the cervix. The cervix opens from 1 to 10 centimeters during the birth process.

t. Effacement — shortening and thinning of the cervix. During childbirth, the cervix becomes a part of the body of the uterus. Measurements are from 0 to 100 percent.

u. Episiotomy — incision through perineum, enlarging the vaginal outlet.

v. Engagement — refers to the entrance of the presenting part into the pelvis.

w. Fetus — developing baby; the developing offspring in the uterus from the second month of pregnancy to birth.

x. Multigravida — a woman who has been pregnant two or more times.

y. Perineum — area between the vaginal opening and the anus.

z. Placenta — also called afterbirth, a special organ of pregnancy which nourishes the fetus. It is expelled following the birth of the baby.

aa. Placenta abruptio — premature separation of the placenta from the uterine wall, this separation resulting in bleeding from the separation site.

bb. Placenta previa — placenta that is implanted in the lower uterine segment, possibly totally or partially covering the opening of the cervix.

cc. Prenatal — refers to the period of time prior to the birth of the baby.

dd. Presenting part — also called presentation, this is the part of the baby that will deliver first.

ee. Primigravida — a woman having her first pregnancy.

ff. Primipara — a woman who has produced one infant of 500 grams or 20 weeks gestation, regardless of whether the infant delivered dead or alive.

gg. Prolapsed cord — the umbilical cord appears in the vaginal orifice before the head of the infant.

hh. Puerperium — the time period following the delivery until about six weeks.

ii. Quickening — feeling of life within the uterus. This is usually noticed during the 16th to the 19th week of gestation.

jj. ROM — rupture of membranes.

kk. Station — the location of the presenting part in relation to the level of the ischial spines (midpelvis). Measures from -5 to +5.

ll. Umbilical cord — cord connecting the baby and the placenta; cord contains blood vessels, usually 19 blood vessels. mm. Uterus — also called womb, a pear-shaped muscular organ which holds and nourishes the developing fetus.

nn. Vagina — also called birth canal, a muscular tube that connects the uterus to the external genitalia; the passage for normal delivery of the fetus.

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Obstetrics Simplified - Diaa M. EI-Mowafi

Obstetric Terms

Presentation

The part of the foetus related to the pelvic brim and first felt during vaginal examination.

The presentation may be:

• Vertex: when the head is flexed.
• Face: when the head is extended.
• Brow: when it is midway between flexion and extension.
• Breech (3.5%).
• Shoulder (0.5%).

Cephalic presentation is the commonest as this makes the foetus more adapted to the pyriform-shaped uterus with the larger buttock in the wider fundus and the smaller head in the narrower lower part of the uterus.

The relation of the foetal back to the right or left side of the mother and whether it is directed anteriorly or posteriorly.

The denominator: is a bony landmark on the presenting part used to denote the position.

• In vertex it is the occiput.
• In face it is the mentum (chin).
• In breech it is the sacrum.
• In shoulder it is the scapula.
• Occipito-anterior positions are more common than occipito- posterior positions because in occipito- anterior positions the concavity of the anterior aspect of the foetus due to its flexion fits with the convexity of the vertebral column of the mother due to its lumbar lordosis.
• Left occipito -anterior (LOA) 60%.
• Right occipito-anterior (ROA) 20%.
• Right occipito posterior (ROP) 15%.
• Left occipito-posterior (LOP)5%.
• Left occipito-transverse (LOT).
• Right occipito transverse (ROT).
• Direct occipito -anterior (DOA).
• Direct occipito-posterior (DOP).

LOA is more common than ROA, and ROP is more common than LOP as in LOA and ROP the head enters the pelvis in the right oblique diameter which is more favourable than the left oblique because:

• anatomically, the right oblique is slightly longer than the left,
• the pelvic colon reduces the length of the left oblique.

The relation of foetal parts to each other.

• Flexion in the majority of cases.
• Extension in face presentation.

The posture in which the 2 parietal bones are at the same level.

Asynclitism

• The posture in which one parietal bone is at a lower level than the other due to lateral inclination of the head.
• Asynclitism is beneficial in bringing the shorter subparietal supraparietal diameter (9 cm) to enter the pelvis instead of the longer biparietal (9.5 cm).
• Slight degree of asynclitism may occur in normal labour.

Anterior parietal bone presentation

• The anterior parietal bone is lower and the sagittal suture is near to the promontory.
• It occurs more in multigravidas due to laxity of the abdominal wall.
• It occurs also in contracted flat pelvis.

Posterior parietal bone presentation

• The posterior parietal bone is lower and the sagittal suture is near to the symphysis.
• It occurs more in the primigravidas due to tense abdominal wall.

Anterior parietal bone presentation is more favourable because:

• The head lies more in the direction of the axis of the pelvic inlet.
• During correction of asynclitism, the head meets only the resistance of the sacral promontory while in posterior parietal bone presentation the head meets the resistance of the whole length of the symphysis pubis.

In posterior parietal bone presentation the head stretches the anterior wall of the lower uterine segment with liability to rupture.

• It is the passage of the widest transverse diameter of the presenting part, which is the biparietal in vertex presentation, through the pelvic inlet.
• The engaged head cannot be easily grasped by the first pelvic grip, but it can be palpated by the second pelvic grip.
• Rule of fifths: 2/5 or less of the foetal head is felt abdominally above the symphysis pubis.
• Vaginally : the vertex is felt vaginally at or below the level of ischial spines.
• Station 0 the vertex at the level of ischial spines.
• Stations -1, 2 and 3 represent 1, 2 and 3 cm respectively above the level of ischial spines.
• Stations +1, +2 and +3 represent 1, 2 and 3 cm respectively below the level of ischial spines.

In the primigravida, engagement of the head occurs in the last 3-4 weeks of pregnancy due to the tonicity of the abdominal and uterine muscles.

In the multipara, the head is usually engaged at the onset of labour or even at the beginning of the second stage due to less tonicity.

Causes of non-engagement

• Large head.
• Hydrocephalus.
• Occipito-posterior positions.
• Malpresentations.
• Multiple pregnancy.
• Placenta praevia.            
• Short cord.
• Polyhydramnios.
• Contracted pelvis.     
• Pelvic tumours.         
• Full bladder or rectum.
• Atony of the abdominal muscles.

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Fetal Presentation, Position, and Lie (Including Breech Presentation)

, MD, Children's Hospital of Philadelphia

Variations in Fetal Position and Presentation

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Presentation refers to the part of the fetus’s body that leads the way out through the birth canal (called the presenting part). Usually, the head leads the way, but sometimes the buttocks (breech presentation), shoulder, or face leads the way.

Position refers to whether the fetus is facing backward (occiput anterior) or forward (occiput posterior). The occiput is a bone at the back of the baby's head. Therefore, facing backward is called occiput anterior (facing the mother’s back and facing down when the mother lies on her back). Facing forward is called occiput posterior (facing toward the mother's pubic bone and facing up when the mother lies on her back).

Lie refers to the angle of the fetus in relation to the mother and the uterus. Up-and-down (with the baby's spine parallel to mother's spine, called longitudinal) is normal, but sometimes the lie is sideways (transverse) or at an angle (oblique).

For these aspects of fetal positioning, the combination that is the most common, safest, and easiest for the mother to deliver is the following:

Head first (called vertex or cephalic presentation)

Facing backward (occiput anterior position)

Spine parallel to mother's spine (longitudinal lie)

Neck bent forward with chin tucked

Arms folded across the chest

If the fetus is in a different position, lie, or presentation, labor may be more difficult, and a normal vaginal delivery may not be possible.

Variations in fetal presentation, position, or lie may occur when

The fetus is too large for the mother's pelvis (fetopelvic disproportion).

The fetus has a birth defect Overview of Birth Defects Birth defects, also called congenital anomalies, are physical abnormalities that occur before a baby is born. They are usually obvious within the first year of life. The cause of many birth... read more .

There is more than one fetus (multiple gestation).

Position and Presentation of the Fetus

Some variations in position and presentation that make delivery difficult occur frequently.

Occiput posterior position

In occiput posterior position (sometimes called sunny-side up), the fetus is head first (vertex presentation) but is facing forward (toward the mother's pubic bone—that is, facing up when the mother lies on her back). This is a very common position that is not abnormal, but it makes delivery more difficult than when the fetus is in the occiput anterior position (facing toward the mother's spine—that is facing down when the mother lies on her back).

Breech presentation

In breech presentation, the baby's buttocks or sometimes the feet are positioned to deliver first (before the head).

When delivered vaginally, babies that present buttocks first are more at risk of injury or even death than those that present head first.

The reason for the risks to babies in breech presentation is that the baby's hips and buttocks are not as wide as the head. Therefore, when the hips and buttocks pass through the cervix first, the passageway may not be wide enough for the head to pass through. In addition, when the head follows the buttocks, the neck may be bent slightly backwards. The neck being bent backward increases the width required for delivery as compared to when the head is angled forward with the chin tucked, which is the position that is easiest for delivery. Thus, the baby’s body may be delivered and then the head may get caught and not be able to pass through the birth canal. When the baby’s head is caught, this puts pressure on the umbilical cord in the birth canal, so that very little oxygen can reach the baby. Brain damage due to lack of oxygen is more common among breech babies than among those presenting head first.

Breech presentation is more likely to occur in the following circumstances:

Labor starts too soon (preterm labor).

Sometimes the doctor can turn the fetus to be head first before labor begins by doing a procedure that involves pressing on the pregnant woman’s abdomen and trying to turn the baby around. Trying to turn the baby is called an external cephalic version and is usually done at 37 or 38 weeks of pregnancy. Sometimes women are given a medication (such as terbutaline ) during the procedure to prevent contractions.

Other presentations

In face presentation, the baby's neck arches back so that the face presents first rather than the top of the head.

In brow presentation, the neck is moderately arched so that the brow presents first.

Usually, fetuses do not stay in a face or brow presentation. These presentations often change to a vertex (top of the head) presentation before or during labor. If they do not, a cesarean delivery is usually recommended.

In transverse lie, the fetus lies horizontally across the birth canal and presents shoulder first. A cesarean delivery is done, unless the fetus is the second in a set of twins. In such a case, the fetus may be turned to be delivered through the vagina.

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SMFM Recommendations: FGR Diagnosis and Management

Learning Objectives and CME/Disclosure Information

This activity is intended for healthcare providers delivering care to women and their families.

After completing this activity, the participant should be better able to:

1. Discuss the definitions associated with fetal growth restriction (FGR) 2. Describe the fetal assessment options when a patient has been diagnosed with FGR

Estimated time to complete activity: 0.25 hours

Disclosure of Conflicts of Interest

Postgraduate Institute for Medicine (PIM) requires faculty, planners, and others in control of educational content to disclose all their financial relationships with ineligible companies. All identified conflicts of interest (COI) are thoroughly vetted and mitigated according to PIM policy. PIM is committed to providing its learners with high quality accredited continuing education activities and related materials that promote improvements or quality in healthcare and not a specific proprietary business interest of an ineligible company.

The PIM planners and others have nothing to disclose. The OBG Project planners and others have nothing to disclose.

Faculty: Susan J. Gross, MD, receives consulting fees from Cradle Genomics, and has financial interest in The ObG Project, Inc.

Planners and Managers : The PIM planners and managers, Trace Hutchison, PharmD, Samantha Mattiucci, PharmD, CHCP, Judi Smelker-Mitchek, MBA, MSN, RN, and Jan Schultz, MSN, RN, CHCP have nothing to disclose.

Method of Participation and Request for Credit

Fees for participating and receiving CME credit for this activity are as posted on The ObG Project website. During the period from 12/01/2022 through 12/01/2024, participants must read the learning objectives and faculty disclosures and study the educational activity.

If you wish to receive acknowledgment for completing this activity, please complete the test and evaluation. Upon registering and successfully completing the test with a score of 100% and the activity evaluation, your certificate will be made available immediately.

Joint Accreditation Statement

In support of improving patient care, this activity has been planned and implemented by the Postgraduate Institute for Medicine and The ObG Project. Postgraduate Institute for Medicine is jointly accredited by the Accreditation Council for Continuing Medical Education (ACCME), the Accreditation Council for Pharmacy Education (ACPE), and the American Nurses Credentialing Center (ANCC), to provide continuing education for the healthcare team.

Physician Continuing Medical Education

Postgraduate Institute for Medicine designates this enduring material for a maximum of 0.25 AMA PRA Category 1 Credit(s)™ . Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Continuing Nursing Education

The maximum number of hours awarded for this Continuing Nursing Education activity is 0.2 contact hours.

SMFM has released guidance on fetal growth restriction (FGR), an evidence-based document that provides a standardized approach to diagnosis and management. The document emphasizes the importance of FGR as a significant pregnancy complication that

…occurs in up to 10% of pregnancies and is second to premature birth as a cause of infant morbidity and mortality. In addition to its significant perinatal impact, FGR also has an impact on long-term health outcomes

Diagnosis of FGR and Definitions

Fetal assessment, fgr prevention and treatment.

• FGR Delivery Timing

ACOG FGR Definition

• FGR: EFW <10th percentile for gestational age
• Small for gestational age (SGA): Newborn birthweight <10th percentile for gestational age

SMFM FGR Definition

• SMFM supports the above ACOG definitions
• Screening performance similar between EFW and AC (see ‘Related ObG Topics’ below)

Note : The term ‘IUGR’ should no longer be used | SMFM document, based on more recent evidence, does not consider symmetric vs asymmetric FGR to be helpful in determining prognosis

Early onset FGR: <32 weeks

• Placental insufficiency
• Hypertensive disorders
• Genetic disorders
• Maternal hypertension
• Doppler abnormalities

Late onset of FGR ≥32 weeks

• Generally, milder clinical course and without flow abnormalities
• EFW <3rd percentile
• Consistent with a more severe form of FGR

KEY POINTS:

• Strong association with fetal anomalies and/or chromosomal disorders (20%)
• Detailed ultrasound CPT code: 76811
• FGR <32 weeks
• FGR and polyhdramnios and/or fetal malformation are detected regardless of gestational age
• Associated with isolated FGR | However, routine testing not recommended due to low CMV incidence
• Offer CMV (PCR) if patient undergoing amniocentesis
• Routine screening is not recommended unless other risk factors are identified

NST (Cardiotocography [CTG])

• Weekly NSTs after viability
• Increase frequency if warranted based on doppler abnormalities or other clinical indications (e.g. comorbidities or risk factors)
• SMFM addresses BPP in the statement and finds that “further studies are required to prove usefulness of BPP”

Umbilical Artery (UA) Doppler Measurement

• UA dopplers every 1 to 2 weeks
• Decreased EDV (flow ratios >95th percentile) or FGR <3rd percentile: Weekly dopplers
• Absent end diastolic velocity (AEDV): 2 to 3 times/week
• Hospitalize
• Administer antenatal corticosteroids
• Perform NST 1 to 2 times/day | Low threshold for delivery depending on clinical scenario

Note : SMFM recommends against routine use of ductus venosus dopplers, middle cerebral artery dopplers, or uterine artery doppler studies in early or late onset FGR | These studies have not been found to lead to improved accuracy over umbilical artery dopplers

• Prenatal aspirin (conflicting data including negative result in ASPRE trial)
• Activity restriction

FGR Delivery

• With oligohydramnios: 34w0d to 37w6d
• Normal UA doppler and EFW 3 to 10th percentile: 38 to 39 weeks
• EFW <3rd percentile (severe FGR): 37 weeks
• Decreased UA flow (S/D, RI, or PI > 95 percentile): 37 weeks
• AEDV: 33 to 34 weeks
• REDV: 30 to 32 weeks

Mode of Delivery

• No strict recommendation for cesarean delivery based on FGR alone
• Reserve for usual fetal and maternal indications
• Mode of delivery for most cases of severe FGR with umbilical artery changes (AEDV or REDV): Cesarean delivery for fetal indication
• Mode of delivery should be determined on a case-by-case basis, taking in to account clinical presentation and maternal preferences

FGR and Preterm

• Administer corticosteroids and magnesium sulfate as per current guidelines

Learn More – Primary Sources:

SMFM Consult Series 52: Diagnosis and Management of Fetal Growth Restriction

ACOG Practice Bulletin 227: Fetal Growth Restriction

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• Cord presentation
• Report problem with article
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Citation, DOI, disclosures and article data

At the time the article was created Yuranga Weerakkody had no recorded disclosures.

At the time the article was last revised Joshua Yap had no financial relationships to ineligible companies to disclose.

• Funic presentation
• Cord (funic) presentation

A cord presentation (also known as a funic presentation or obligate cord presentation ) is a variation in the fetal presentation  where the umbilical cord points towards the internal cervical os or lower uterine segment.

It may be a transient phenomenon and is usually considered insignificant until ~32 weeks. It is concerning if it persists past that date, after which it is recommended that an underlying cause be sought and precautionary management implemented.

On this page:

Epidemiology, radiographic features, treatment and prognosis, differential diagnosis.

• Cases and figures

The estimated incidence is at ~4% of pregnancies.

Associations

Recognized associations include:

marginal cord insertion from the caudal end of a low-lying placenta

uterine fibroids

uterine adhesions

congenital uterine anomalies that may prevent the fetus from engaging well into the lower uterine segment

cephalopelvic disproportion

polyhydramnios

multifetal pregnancy

long umbilical cord

Color Doppler interrogation is extremely useful and shows cord between the fetal presenting part and the internal cervical os. However, unlike a vasa previa , the placental insertion is usually normal.

As the complicating umbilical cord prolapse can lead to catastrophic consequences, most advocate an elective cesarean section delivery for persistent cord presentation in the third trimester 3 .

Complications

It can result in a higher rate of umbilical cord prolapse .

For the presence of umbilical cord vessels between the fetal presenting part and the internal cervical os on ultrasound consider:

vasa previa

• 1. Ezra Y, Strasberg SR, Farine D. Does cord presentation on ultrasound predict cord prolapse? Gynecol. Obstet. Invest. 2003;56 (1): 6-9. doi:10.1159/000072323 - Pubmed citation
• 2. Kinugasa M, Sato T, Tamura M et-al. Antepartum detection of cord presentation by transvaginal ultrasonography for term breech presentation: potential prediction and prevention of cord prolapse. J. Obstet. Gynaecol. Res. 2007;33 (5): 612-8. doi:10.1111/j.1447-0756.2007.00620.x - Pubmed citation
• 3. Raga F, Osborne N, Ballester MJ et-al. Color flow Doppler: a useful instrument in the diagnosis of funic presentation. J Natl Med Assoc. 1996;88 (2): 94-6. - Free text at pubmed - Pubmed citation
• 4. Bluth EI. Ultrasound, a practical approach to clinical problems. Thieme Publishing Group. (2008) ISBN:3131168323. Read it at Google Books - Find it at Amazon

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Chapter 6. Normal Pregnancy and Prenatal Care

Helene B. Bernstein, MD, PhD; George VanBuren, MD

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• Normal Pregnancy
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Pregnancy (gestation) is the physiologic process of a developing fetus within the maternal body. Several terms are used to define the developmental stage of human conception and the duration of pregnancy. For obstetric purposes, the gestational age or menstrual age is the time elapsed since the first day of the last normal menstrual period (LNMP), which actually precedes the time of oocyte fertilization. The gestational age is expressed in completed weeks. The start of the gestation (based on the LNMP) is usually 2 weeks before ovulation, assuming a 28-day regular menstrual cycle. The developmental or fetal age is the age of the conception calculated from the time of implantation, which is 4 to 6 days after ovulation is completed. The menstrual gestational age of pregnancy is calculated at 280 days or 40 completed weeks. The estimated due date (EDD) may be estimated by adding 7 days to the first day of the last menstrual period and subtracting 3 months plus 1 year (Naegele's rule).

The period of gestation can be divided into units consisting of 3 calendar months each or 3 trimesters. The first trimester can be subdivided into the embryonic and fetal periods. The embryonic period starts at the time of fertilization (developmental age) or at 2 through 10 weeks' gestational age. The embryonic period is the stage at which organogenesis occurs and the time period during which the embryo is most sensitive to teratogens. The end of the embryonic period and the beginning of the fetal period occurs 8 weeks after fertilization (developmental age) or 10 weeks after the onset of the last menstrual period.

Definitions

The term gravid means “pregnant”; gravida is the total number of pregnancies that a women has had, regardless of the outcome. Parity is the number of births, both before and after 20 weeks' gestation, and comprises 4 components:

Full-term births

Preterm births: having given birth to an infant (alive or deceased) weighing 500 g or more, or at or beyond 20 completed weeks (based on the first day of the last menstrual period)

Abortions: pregnancies ending before 20 weeks, either induced or spontaneous

Living children

When gravidity and parity are calculated as part of the obstetric history, multiple births are designated as a single gravid event, and each infant is included as part of the parity total.

Live birth is the delivery of any infant (regardless of gestational age) that demonstrates evidence of life (eg, a heartbeat, umbilical cord pulsation, voluntary or involuntary movement), independent of whether the umbilical cord has been cut or the placenta detached. An infant is a live-born human from the moment of birth until the completion of 1 year of life (365 days).

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1.8: Obstetrics

• Last updated
• Save as PDF
• Page ID 64957

• Stacey Grimm, Coleen Allee, Elaine Strachota, Laurie Zielinski, Traci Gotz, Micheal Randolph, and Heidi Belitz
• Nicolet College via Wisconsin Technical College System

Learning Objectives

• Identify the common processes in obstetrics
• Describe the specialty of obstetrics
• Spell the medical terms used in obstetrics and use correct abbreviations
• Identify the medical specialties associated with obstetrics
• Explore common complications and procedures related to obstetrics

Obstetric Word Parts

Click on prefixes, combining forms, and suffixes to reveal a list of word parts to memorize related to obstetrics., query \(\pageindex{1}\), introduction to obstetrics.

Obstetrics is a specialty that is concerned with the mother and fetus during pregnancy, childbirth and the immediate postpartum period. Obstetricians study obstetrics and gynecology and are referred to as OB/GYN Obstetrics and Gynecology.

Watch this video:

A YouTube element has been excluded from this version of the text. You can view it online here: https://pb.libretexts.org/med/?p=87

Media 8.1. R eproductive System, Part 4 – Pregnancy & Development: Crash Course A&P #43 [Online video]. Copyright 2015 by CrashCourse .

Obstetrics Medical Terms

Query \(\pageindex{2}\), fertilization.

Fertilization occurs when a sperm and an oocyte (egg) combine. Because each of these reproductive cells is a haploid cell containing half of the genetic material needed to form a human being, their combination forms a diploid cell. This new single cell is called a zygote.

Most of the time, a woman releases a single egg during an ovulation cycle.

• Two zygotes form, implant, and develop, resulting in the birth of dizygotic (or fraternal) twins . Because dizygotic twins develop from two eggs fertilized by two sperm, they are no more identical than siblings born at different times.
• Less common, one zygote can divide into two separate offspring during early development. This results in the birth of monozygotic (or identical) twins .

A full-term pregnancy lasts approximately 270 days (approximately 38.5 weeks) from conception to birth. Because it is easier to remember the first day of the last menstrual period (LMP) than to estimate the date of conception, obstetricians set the due date as 284 days (approximately 40.5 weeks) from the LMP. This assumes that conception occurred on day 14 of the woman’s cycle, which is usually a good approximation. The 40 weeks of an average pregnancy are usually discussed in terms of three trimesters, each approximately 13 weeks. During the second and third trimesters, the pre-pregnancy uterus is about the size of a fist and grows dramatically to contain the fetus, causing a number of anatomical changes in the mother.

The process of childbirth can be divided into three stages (see Figure 8.1):

• cervical dilation
• expulsion of the newborn
• after birth

For vaginal birth to occur, the cervix must dilate fully to 10 cm in diameter, wide enough to deliver the newborn’s head. The dilation stage is the longest stage of labor and typically takes 6-12 hours. However, it varies widely and may take minutes, hours, or days, depending in part on whether the mother has given birth before. In each subsequent labor, this stage tends to be shorter.

Concept Check

• How is a due date determined?
• Explain the difference between a monozygotic pregnancy and a dizygotic pregnancy .

Homeostasis in the Newborn: Apgar Score

In the minutes following birth, a newborn must undergo dramatic systemic changes to be able to survive outside the womb. An obstetrician, midwife, or nurse can estimate how well a newborn is doing by obtaining an Apgar score (Fig 8.2). The Apgar score was introduced in 1952 by the anesthesiologist Dr. Virginia Apgar as a method to assess the effects on the newborn of anesthesia given to the laboring mother. Healthcare providers now use it to assess the general well-being of the newborn, whether or not analgesics or anesthetics were used.

The technique for determining an Apgar score is quick and easy, painless for the newborn, and does not require any instruments except for a stethoscope. A convenient way to remember the five scoring criteria is to apply the mnemonic APGAR:

• A ppearance (skin color)
• P ulse (heart rate)
• G rimace (reflex)
• A ctivity (muscle tone)
• R espiration

Of the five Apgar criteria, heart rate and respiration are the most critical. Poor scores for either of these measurements may indicate the need for immediate medical attention to resuscitate or stabilize the newborn. In general, any score lower than 7 at the 5-minute mark indicates that medical assistance may be needed. A total score below 5 indicates an emergency situation. Normally, a newborn will get an intermediate score of 1 for some of the Apgar criteria and will progress to a 2 by the 5-minute assessment. Scores of 8 or above are normal.

Obstetrics Medical Terms not Easily Broken into Word Parts

Query \(\pageindex{3}\), obstetrics abbreviations, query \(\pageindex{4}\), medical terms in context, query \(\pageindex{5}\), procedures related to obstetrics, in vitro fertilization (ivf).

IVF, which stands for in vitro fertilization, is an assisted reproductive technology. In vitro, which in Latin translates to in glass, refers to a procedure that takes place outside of the body. There are many different indications for IVF. For example, a woman may produce normal eggs, but the eggs cannot reach the uterus because the uterine tubes are blocked or otherwise compromised. A man may have a low sperm count, low sperm motility, sperm with an unusually high percentage of morphological abnormalities, or sperm that are incapable of penetrating the zona pellucida of an egg. Figure 8.3 illustrates the steps involved in IVF.

Test Yourself

Query \(\pageindex{6}\).

[CrashCourse]. (2019, November 23). Reproductive System, Part 4 – Pregnancy & Development: Crash Course A&P #43 [Video]. YouTube. https://youtu.be/BtsSbZ85yiQ

Unless otherwise indicated, this chapter contains material adapted from Anatomy and Physiology (on OpenStax ), by Betts, et al. and is used under a a CC BY 4.0 international license . Download and access this book for free at https://openstax.org/books/anatomy-and-physiology/pages/1-introduction .

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StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.

StatPearls [Internet].

Obstetric ultrasound.

Meghan K. Herbst ; Dawood Tafti ; Meaghan M. Shanahan .

Affiliations

Last Update: May 22, 2023 .

• Continuing Education Activity

Ultrasound is a noninvasive diagnostic modality that can quickly confirm an intrauterine pregnancy at the bedside, significantly shortening the length of stay for pregnant patients and avoiding the use of contrast or radiation. Point-of-care pelvic ultrasound in the hands yields the greatest diagnostic potential in the first trimester of pregnancy. This activity illustrates how an obstetric ultrasound can help detect disorders of pregnancy and highlights the role of the interprofessional team in caring for patients undergoing obstetrical ultrasound.

• Describe the indications for obstetric ultrasound.
• Summarize the technique involved in performing an obstetric ultrasound.
• Review the clinical significance of the obstetric ultrasound during pregnancy.
• Explain the importance of optimize coordination amongst interprofessional team members to enhance the delivery of care to pregnant patients with the use of the obstetric ultrasound.
• Introduction

Obstetricians first used ultrasound to diagnose an early intrauterine pregnancy in the 1960s and 1970s. Emergency physicians adapted ultrasound for point-of-care use in the 1990s. Ultrasound is a noninvasive diagnostic modality that can quickly confirm an intrauterine pregnancy at the bedside, significantly shortening the emergency department (ED) length of stay for pregnant patients.[18] [1]  Point-of-care pelvic ultrasound in the hands of emergency medicine providers yields the highest diagnostic potential in the first trimester period of pregnancy. [2] [3]  For this reason, the remainder of the article focus is on ultrasound in first-trimester pregnancy. 

• Anatomy and Physiology

The landmarks of the uterus are the bladder and vaginal stripe. The bladder is located anterior and inferior to the uterus, and the vaginal stripe is a hyperechoic line that is located posterior to the bladder. The vaginal stripe ends at the cervix, and the uterine fundus usually curves up anteriorly (anteverted uterus, approximately 80% of women), but in a smaller subset of females, curves posteriorly (retroverted uterus). The endometrium usually appears as a hyperechoic line in the center of the uterine fundus.

An intrauterine pregnancy (IUP) is confirmed on ultrasound when an intrauterine gestational sac containing a yolk sac and/or a fetal heart rate is visualized with an endomyometrial mantle greater than 7mm. Lack of any of these features would be classified as no definitive intrauterine pregnancy (NDIUP). [4] [5] [6]

• Indications

Vaginal bleeding

• Confirmation of an IUP in the setting of vaginal bleeding in a first-trimester pregnancy effectively rules out an ectopic pregnancy if the pregnancy was conceived without reproductive endocrinology assistance. The diagnosis, in this case, is usually a threatened abortion. NDIUP in the setting of vaginal bleeding warrants further workup for an ectopic pregnancy. [2]

Positive pregnancy test, asymptomatic

• Emergency physicians are often the first providers to ultrasound first trimester pregnancies, as obstetricians will ask a patient to schedule her first appointment at approximately 8 weeks gestation according to her last menstrual period. For this reason, patients will often present to the ED after finding out they are pregnant from a home pregnancy test, sometimes for no other reason other than to formally diagnose the pregnancy. Under these circumstances, an ultrasound should be attempted to confirm the presence of an IUP, as well as to date the fetus if present. While it was once thought the earlier a pregnancy is dated, the more accurate the gestational age, the difference may be too small to justify. [7] However, dating the gestation by using the “crown-rump-length” calculation (CRL) over the longest dimension of the fetal pole without including the yolk sac would be appropriate and important to communiicate to the patient's obstetrician, especially if the patient delayed her first obstetric appointment and ultrasound. [8] If NDIUP is appreciated in an asymptomatic patient, a serum beta-hCG should be ordered, and the patient should arrange for repeat testing in 48 hours with obstetrician follow-up to ensure the hormone is rising appropriately.

Abdominal pain

• Confirmation of an IUP in the setting of abdominal pain effectively rules out an ectopic pregnancy if the pregnancy was conceived without reproductive endocrinology assistance, given the rare incidence of heterotopic pregnancy in these women.
• Confirmation of a live ectopic pregnancy, defined as a gestational sac containing a yolk sac or fetal heartbeat outside the uterus or with an endomyometrial mantle less than or equal to 7 mm (which supports the diagnosis of an interstitial ectopic pregnancy) should lead to prompt obstetrician consultation for operative management.
• In an hCG-positive female with abdominal pain, where the uterus reveals NDIUP as well as free fluid in the pelvis, prompt obstetrician consultation should be sought. If there is additional free fluid in Morison’s pouch, these findings carry high specificity for ectopic pregnancy needing operative management. [9]

Hypotension

• Free peritoneal fluid in Morison’s pouch or the pelvis in a patient with an NDIUP who has a positive urine pregnancy test is highly specific for an ectopic pregnancy requiring operative management. [9]

Hyperemesis gravidarum

• A twin gestation or molar pregnancy may explain significant nausea and vomiting.

If the transabdominal pelvic ultrasound shows NDIUP, a transvaginal ultrasound is indicated. If a female is or has received reproductive endocrine assistance in getting pregnant, early consultation with her reproductive endocrinologist is recommended. [10]

• Contraindications

There are no absolute contraindications to performing a transabdominal pelvic ultrasound in early pregnancy. Care should be taken not to scan over a wound or incision to avoid contamination and infection. A transvaginal ultrasound is contraindicated in the setting of hypotension. It is also recommended to use settings that expose the first-trimester fetus to as low as reasonably achievable (ALARA) frequencies by avoiding color and spectral Doppler during the exam.

First-trimester pregnancy transabdominal ultrasound should be performed with a low-frequency probe, ideally with a large convex footprint. If a transvaginal ultrasound exam is indicated, an endocavitary probe with sheath can improve visualization of the uterus and adnexal structures. A high-level disinfectant system is needed to clean the endocavitary probe between uses.

A trained provider can perform first-trimester pregnancy ultrasound. Emergency physicians are required to correctly perform and interpret a minimum of 25 to 50 cardiac ultrasound exams upon residency graduation. [3]

• Preparation

Transabdominal Pelvic Ultrasound

Ideally, the patient’s bladder will be full, as it provides an acoustic window for visualizing the uterus. The patient should be lying supine on a stretcher with her abdomen exposed and towels tucked around the gown and undergarment edges to keep them dry from the ultrasound gel. For dominant right-hand operators, the ultrasound machine should be positioned at the patient’s anatomic right, plugged in (if applicable) and turned on. The lights should be dimmed if possible. [11]

Transvaginal Ultrasound

A transabdominal pelvic ultrasound should always be performed before a transvaginal ultrasound. The patient’s bladder should be as empty as possible before performing a transvaginal ultrasound, to allow the probe to get as close to the uterus and adnexa as possible. To allow adequate visualization of an anteverted uterus, the patient should be positioned in a stretcher with stirrups and her pelvis at the edge of the stretcher, or her pelvis should be elevated approximately 8 cm to 10 cm with an upside-down bedpan and two to three folded chucks. [11]

• Technique or Treatment

A low-frequency convex probe is best for a transabdominal pelvic ultrasound. Alternatively, a phased array probe can be used if a convex probe is not available. The settings on the ultrasound machine should be set to "obstetrics" or “pregnancy.” The first view should be a sagittal view through the uterus. The convex probe is placed just superior to the pubic symphysis, with the indicator directed superiorly. The footprint should be directed slightly inferiorly. Structures closest to the probe appear at the top of the screen, and structures further away appear toward the bottom of the screen, so in this view, the top of the screen is anterior, and the bottom of the screen is posterior. The left of the screen represents the direction the indicator is pointing toward, which in this view is superior or cephalad, and the right of the screen is inferior or caudad. The bladder, if full, will take up most of the anterior (top) portion of the screen, ending just superior to the pubic symphysis on the right of the screen. Posterior to the bladder is the vaginal stripe, a hyperechoic line starting at the inferior (right) side of the screen and leading to the cervix and uterus. Fanning to the right and left until the uterus disappears in both directions allows for a complete view of the uterus. If a gestational sac is visualized, interrogation for a yolk sac or fetal heartbeat within the gestational sac, as well as measurement of the thinnest endomyometrial mantle around the gestational sac should take place to confirm the presence of an IUP. If there is a fetal heartbeat, Motion-Mode (M-mode) should be employed to calculate the fetal heartbeat. When selecting M-mode, move the M-mode line to where it crosses through the flicker of the fetal heartbeat before graphing the motion across that line over time. A regular pattern of peaks and troughs should trace out on the screen. Freeze that image and use your calculations menu to select the most appropriate calipers for calculating the fetal heartbeat. By placing your calipers at the start of one peak to the start of the next, the machine should calculate the fetal heart rate based on that distance. Some machines require that the calipers be placed over two beats (start of one peak to the start of the second peak after that peak) to calculate an average fetal heart rate.

Transvaginal ultrasound: The endocavitary probe is a high-frequency transducer with a longer handle compared to other transducers. The footprint is small and tightly curved. The transducer shape in its entirety is analogous to a rifle, where the indicator is the side opposite the “trigger.” Before performing a transvaginal ultrasound, a transabdominal ultrasound should be performed to look for uterine landmarks (vaginal stripe and bladder) as well as an IUP. If NDIUP is appreciated, have the patient empty her bladder and when she returns, place an upside-down bedpan with several chucks underneath her pelvis and, while keeping the patient draped, insert the probe with the indicator pointing anteriorly (toward the ceiling). Watch the decompressed bladder move out of view towards the top left side of the screen. When the bladder is barely out of sight, the probe is at the appropriate depth and by fanning the probe to the left and right, obtain a sagittal view of the uterus. The top of the screen represents the inferior aspect of the patient (cervix), the bottom of the screen represents the superior aspect of the patient, the left of the screen represents the anterior aspect of the patient, and the right of the screen represents the posterior aspect of the patient. The Pouch of Douglas, therefore, is the right lower aspect of the screen. While fanning through the uterus, look for a yolk sac and/or fetal heartbeat to diagnose an IUP. 

After interrogating for an IUP as well as for free fluid in the Pouch of Douglas, rotate your probe 90 degrees counterclockwise to visualize the uterus in a transverse (more accurately, coronal) plane, where the top of the screen is still inferior, the bottom of the screen is superior, the left of the screen is the patient’s right, and the right of the screen is the patient’s left. In this plane, the uterus tapers on either side where the fallopian tubes take off. On ultrasound, it is difficult to appreciate the fallopian tubes unless there is a tubal ectopic, or fluid within the tubes (hydrosalpinx or pyosalpinx). However, the areas where the uterus tapers in size on either side are called the cornua. The ovaries typically sit between the cornua and the more lateral iliac vessels and are slightly more hypoechoic than the uterus. After locating the cornua with the indicator pointing toward the patient’s right side, and the footprint steered toward the patient’s right side, fan anteriorly and posteriorly until either an undefined hypoechoic area or a defined ovary with anechoic follicles is appreciated. If an undefined hypoechoic area is seen, apply gentle pressure with the probe until an ovary comes into view. Typical ovarian dimensions are 1.5 cm x 1.5 cm x 3 cm. A simple ovarian cyst is 2.5 cm or greater, whereas a follicle is smaller than 2.5 cm. A corpus luteum cyst, which tends to have a thicker wall than a simple cyst, is frequently appreciated in the first 12 weeks of pregnancy. [11]

• Complications

Pelvic ultrasound, like most diagnostic ultrasound applications, is associated with little if any risk. There may be some associated discomfort when pressure is applied to the probe both in transabdominal and transvaginal views.

• Clinical Significance

Pelvic ultrasound is a rapid, inexpensive, safe application that expedites the diagnosis of intrauterine pregnancy. [12] Pelvic ultrasound can also expedite management in the setting of a ruptured ectopic pregnancy when free fluid and NDIUP is present. [9]

• Enhancing Healthcare Team Outcomes

Pregnany is managed by an interprofessional team that includes nurses and pharmacists. It is important for healthcare workers to know that an obstetric ultrasound is a useful technique for identifying several pregnancy related pathologies. The technique is portable, does not use contrast and can be performed at the bedside.

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Sagittal transabdominal pelvis view Contributed by Meghan Herbst, MD

Disclosure: Meghan Herbst declares no relevant financial relationships with ineligible companies.

Disclosure: Dawood Tafti declares no relevant financial relationships with ineligible companies.

Disclosure: Meaghan Shanahan declares no relevant financial relationships with ineligible companies.

This book is distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ), which permits others to distribute the work, provided that the article is not altered or used commercially. You are not required to obtain permission to distribute this article, provided that you credit the author and journal.

• Cite this Page Herbst MK, Tafti D, Shanahan MM. Obstetric Ultrasound. [Updated 2023 May 22]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-.

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Similar articles in PubMed

• Outcome of patients with an indeterminate emergency department first-trimester pelvic ultrasound to rule out ectopic pregnancy. [Acad Emerg Med. 2004] Outcome of patients with an indeterminate emergency department first-trimester pelvic ultrasound to rule out ectopic pregnancy. Tayal VS, Cohen H, Norton HJ. Acad Emerg Med. 2004 Sep; 11(9):912-7.
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