Quiz 1 Study Guide

UT 609A - OB 1

Spontaneous abortion

• Physiological termination prior to 20 weeks gestation

  • Hemorrhage of decidua basalis → inflammation and necrosis around region of implantation → detachment of conceptus → UT contractions and expulsion of intrauterine contents via dilated CVX

• US role in spontaneous abortions: access presence and amount of retained product of conception in UT cavity 

• Common etiology: endocrine factors, failure of corpus luteum, chromosomal causes, diabetes, PCOS, smoking, etc.

Complete abortion

• Evacuation of all products of conception

• Clinical signs:

  • Rapid decline of HCG levels

  • Vaginal bleeding w/ tissue/clots

  • Cramping 

  • Disappearance of pregnancy symptoms

  • Cessation of pain and bleeding after conceptus is passed

• US findings:

  • Empty uterus with “clean” endometrial stripe

  • Uterine enlargement

Incomplete abortion

• Partial evacuation of products of conception (POC)

• Clinical signs:

  • Slow fall or plateauing of HCG levels

  • Moderate cramping

  • Persistent, heavy bleeding

• US findings:

  • Presence of complex collection of echoes in endometrium of retained products of conception (RPOC)

    • Air bubbles

    • Retained bony fragments

  • Hematoma 

  • Persistence of trophoblastic waveforms near EC 5 days post abortion

Anembryonic pregnancy (AKA blighted ovum)

• Intrauterine gestational sac is empty

• Embryonic demise or failure of embryo to develop

• Clinical signs:

  • Uterus small for dates

  • Variable HCG levels

  • Vaginal spotting

  • Closed CVX

• US findings:

  • No identifiable embryo in GS of >25 mm

  • Absence of “double sac sign” or “double decidual sign”

Threatened abortion

• Bleeding, spotting, or cramping with a closed cervical OS

• 50/50 odds for normal outcome or spontaneous abortion

• Clinical signs:

  • No reliable signs

    • More clinical than sonographic

  • Vaginal bleeding < 20 weeks

  • Lower abdominal ache

Imminent/inevitable abortion

• Occurs when 2+ clinical signs are present

• Clinical signs:

  • Effacement of CVX

  • Cervical dilation >3 cm

  • Rupture of membranes 

  • Bleeding for >7 days

  • Persistent cramping

• US findings:

  • Gestational sac seen in CVX or LUS

  • Cervical dilatation

  • Sonolucent crescent around gestational sac

Missed abortion (AKA silent miscarriage)

• Fetus is no longer alive but body does not recognize pregnancy loss or expels tissue

• US findings:

  • Embryo in gestational sac w/o fetal heart tones

Ectopic pregnancy

• Implantation of conceptus outside endometrial cavity 

• Locations: 

  • Fallopian tubes (95%)

    • Ampulla (70%) - most common location in FT

  • Uterine, cervical (high morbidity and mortality), abdominal, ovary 

• Cause - anything interfering with passage of ovum to UT cavity 

• Leading cause of maternal mortality and morbidity

• If HCG > 2000 + no IUP → investigate for ectopic pregnancy

• Treatment - methotrexate (MTX) for ectopic w/o heartbeats 

  • Surgery to remove mass

Risk factors for ectopic pregnancy

• Increase in frequency is most likely due to PID and ART use

  • Prior ectopic

  • PID

  • Assisted reproductive technology (ART)

  • IUDs

  • Smoking

  • Increased maternal age

Clinical findings of an ectopic pregnancy

• Clinical triad: vaginal bleeding, pain, and palpable mass

• Variable HCG levels 

• Adnexal mass

• Pelvic pain and bleeding

• Leukocytosis

• Fever

• Pain referred to shoulder → intraperitoneal hemorrhage

Clinical triad of ectopic pregnancy

• Vaginal bleeding

• Pain

• Palpable mass

US findings of ectopic pregnancies

• Extrauterine GS w/ yolk sac

• Empty uterus on EV, if hCG levels are > 800-1000 mIU/mL

• Adnexal mass, separate from ovaries

• Free fluid in cul-de-sac, adnexa, or pericolic gutters

• Concomitant intra- or extrauterine implantation

• Ring of fire - trophoblastic tissue surrounding conceptus

• Donut sign

Pitfalls when scanning for ectopic pregnancies

• Pseudogestational sacs

• Corpus luteum cyst vs. adnexal ectopic both have ring of fire appearance

  • Corpus luteum cyst - more hypoechoic

  • Adnexal ectopic - echogenic decidual donut

Heterotopic pregnancy

Presence of multiple gestations, one in UT cavity and other outside of UT 

Cornual ectopic pregnancy

• Occurs in uterine horn

• High susceptibility of rupturing 

• Associated w/ uterine anomalies 

• Most deadly along w/ interstitial

  • High vascularity from UT arteries

Intramural ectopic pregnancy

• Gestational sac implanted into the myometrium

• Causes: past surgical procedures

  • Ex: myomectomy or C-section

• On the rise due to rise of C-section usage

Cervical ectopic pregnancy

• Implantation in endocervical canal

• Risk factors:

  • Previous D&C

  • Amniotic anomalies 

  • Endometriosis

  • IUD

  • IVF

C-section scar ectopic pregnancy

Gestational sac implants into myometrium of previous c-section scar

Ovarian ectopic pregnancy

• Gestational sac implants in the ovary

• Increasing incidence due to PID and IUD usage

  • IUD prevents implantation into UT 

• Symptoms: low abdominal pain and bleeding

Abdominal ectopic pregnancy

• Gestational sac implants into abdominal cavity

• Symptoms: general malaise, nausea, vomiting, vaginal bleeding

• Risk factors: PID, endometriosis, tubal damage

• Possible sites: spleen, UT surface, liver, diaphragm, bowel, etc.

Acute rupture of tubal ectopic pregnancy

Ectopic pregnancy not seen due to amount of blood and clot

Gestational sac

Well-defined circle of echoes in central fundus of UT

The gestational sac grows ___ mm/day prior to 6 weeks

1

How to measure mean sac diameter (MSD)

length + width + height / 3

Double bleb sign

• Sonographic feature of gestational sac containing yolk sac + adjacent amniotic sac

• Appearance of 2 small bubbles

Trilaminar disk

Early stage in development of triploblastic organisms

Gastrulation

Formation of primitive streak along epiblast disc

Primitive streak

• Formed from proliferation and movement of epiblast cells to the median plane of embryonic disc

• Once it appears, can identify embryo’s craniocaudal axis

Sacrococcygeal teratoma (SCT)

• Most common neoplasm in newborn

• Formed from remnants of primitive streak

• Benign tumor that has elements of incomplete differentiated germ layers

• Mostly found in females

Three germinal layers of the trilaminar disc

• Ectoderm - remaining epiblast cells

  • Epidermis, nails, hair, sebaceous glands

• Mesoderm - infiltrated epiblast cells

  • Muscles, skeleton, cartilage

• Endoderm - remaining hypoblast cells

  • Lines GI tract, aka stomach, colon, liver, bladder

Yolk sac

• Provides some of the first cells + circulation necessary for life

  • Produces RBCs needed for primitive circulatory system

  • Source of nutrients 

• Connected to embryo via vitelline duct 

• Located within chorionic cavity 

• Emergence: first few days of gestation

• ~ 7 weeks, role diminishes and is supplanted by placenta

• Disappears around week 10

• Useful in assessing amnion number in multiple gestations

• US appearance: spherical w/ sonolucent center and clearly defined echogenic walls

The yolk sac should always be visualized when the MSD > ___ mm (~ 5.5 weeks)

8

Trophoblast

Thin layer of cells that protect developing embryo, attaches it to the wall of UT, and forms part of placenta

Gestational trophoblastic disease (GTD)

• Group of interrelated tumors originating from placenta 

  • Usually occurs shortly after UT implantation of fertilized ovum

• Histological confirmation is mandatory for Dx

  • Gold standard = histological confirmation post-curettage

Clinical findings of GTD

• Enlarged UT 

• Grossly elevated hCG levels

• Hyperemesis gravidarum - severe nausea and vomiting

• UT bleeding in first trimester

• Absence of FHT

• Theca-lutein cysts (50% of time due to elevated hCG)

• Onset of preeclampsia - HTN, proteinuria, edema, headaches

• Hyperthyroidism

Molar pregnancy association w/ very early onset preeclampsia

• Molar placentas produce more anti-angiogenic proteins → produce systemic endothelial dysfunction → HTN, proteinuria, etc. 

  • Endothelium - thin membrane lining heart and blood vessels

  • Endothelial cells - controls vascular relaxation and contraction

Forms of GTD

• Complete hydatidiform mole

• Partial mole

• Mole w/ coexisting fetus

• Hydroponic degeneration of placenta

• Persistent trophoblastic neoplasia

• Invasive mole (chorioadenoma destruens)

• Uterine choriocarcinoma (gestational choriocarcinoma)

• Placental site trophoblastic tumor

Complete hydatidiform mole

• Most common form of GTD

• Chorionic villi are diffusely hydropic + surrounded by trophoblasts

• No fetal tissue identified

• Maternal risk factors: young age or over 40 y/o

• GTD → high hCG → theca-lutein cysts (50% of cases)

US findings of complete hydatidiform mole

• Endometrial cavity filled with heterogeneous echogenic material 

• Vesicular appearance - multiple cysts

• Increased UT size 

• Fluid collection around molar mass 

• Mimics appearance of degenerating myoma

Partial mole

• Triploidy - fetus w/ extra set of chromosomes

  • Normal 23 pairs of chromosomes, 46 total

• Fetus is usually non-viable and triploid due to structural abnormality 

  • Will always be evacuated after diagnosis

US findings of partial mole

• Molar placenta - grossly enlarged placenta + cystic areas

• focal/diffuse areas of increased echogenicity in or around placenta 

• Presence of fetal tissue

Mole w/ coexisting fetus

• Outside of realm of true GTD

• Technically 2 conceptions

  • 1. Normal pregnancy

  • 2. Molar pregnancy

US findings of mole w/ coexisting fetus

Similar to partial mole but with viable and complete fetal tissue

Hydroponic degeneration of placenta

• Characterized by presence of numerous cystic areas within enlarged placenta 

• Not considered part of GTD spectrum 

• Associated w/ partial mole and paternal triploidy

• Simple hydropic degeneration in first trimester → increased risk of fetal demise

Persistent trophoblastic neoplasia

• Pregnancy complication following GTD 

• Treatment of molar pregnancy → molar tissue still remaining → grows into tumor

• Just under 100% cure rate 

• Treatment - chemotherapy 

• Highest risk - severe histological types of initial trophoblastic proliferation

• Lowest risk - partial molar pregnancy

US findings of persistent trophoblastic neoplasia

• Heterogeneous uterine mass 

• Multiple lacunae surrounding mass w/ high-amp low-resistance blood flow

Invasive mole (AKA chorioadenoma destruens)

• Rare molar tissue that invades myometrium and adjacent anatomic structures

• Malignant non-metastatic form of GTD

US findings of invasive mole

• Focal/diffuse echogenic material in endometrium

  • Possible extension to myometrium

• Irregular sonolucent areas surrounding trophoblastic tissue

• Swiss-cheese appearance 

• Hypervascular

• Theca-lutein cysts

Uterine choriocarcinoma (AKA gestational choriocarcinoma)

• Pure epithelial tumor

• Implantation of trophoblast → two layers

  • Synctiotrophoblast (ST)

  • Cytotrophoblast 

• Absence of hydropic villi

• Appearance of sheets/foci of trophoblasts identified w/ background of hemorrhage and necrosis

• Malignant metastatic form of GTD

US findings of uterine choriocarcinoma

• Enlarged UT

• Eccentrically situated irregular complex mass in UT 

• Low-resistance blood flow around mass

Placental site trophoblastic tumor

• Arises from placental implantation site

• Tumor can infiltrate myometrium and grown between smooth-muscle cells

Human chorionic gonadotropin (HCG)

•  Glycoprotein secreted by physiologically active trophoblastic tissue

  • Presence of HCG in maternal blood = strongest indicator of presence of gestation

• Shows ~6-8 days post conception

• Doubles every 2 days (~ 48 hours)

• Peaks at 10 weeks' gestation before declining and stabilizing

• Undetectable HCG → excludes gestation from anywhere in body 

• If HCG plateaus or falls prematurely → pregnancy may not be viable

• Most sensitive test: quantitative serum (blood) test

HCG doubles every __ days

2

HCG peals at __ weeks' gestation before declining and stabilizing

10

Discriminatory levels of HCG

• Levels in which intrauterine pregnancy (IUP) is always going to be seen

  • Endovaginal: > 800-1000 mIU/mL 

  • Transabdominal: > 1800 mIU/mL

• Pregnancy not seen in endometrial cavity at these levels → failed pregnancy highly suspected

Notochord

• First mesodermal tissue to form

• Formation of the primitive node and streak and the rod-shaped group of cells that define the body’s primary supporting axis

  • Forms within embryonic plate between ectoderm and endoderm

• Source of midline signals that pattern the surrounding tissues + acts as skeletal element for developing embryo

• Early embryo, induces development of structures

• Late embryo, develops into nucleus pulposus of the discs of the spinal column

Bradycardia

Abnormally slow heart action

Tachycardia

Abnormally rapid heart action

FHR at 5-6 weeks

100-115 bpm

FHR after 9 weeks