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OBSTETRICS A little bit of everything or, a whole lot of not much Holdorf Second and Third Trimester Placenta Placenta Development The placenta is a mateno-fetal organ which begins developing at implantation of the blastocyst and is delivered with the fetus at birth. This is a normal fetal ultrasound performed at 17 weeks gestation. In the foreground to the left and middle of the screen, you can see the placenta, following the curve of the uterus. Placental Positions Placental development may occur on any side of the gestational sac: Anterior Posterior Lateral (right/left) Fundal Fundal Posterior Umbilical Cord The umbilical cord is the lifeline that attaches the placenta to the fetus. The umbilical cord is made up of three blood vessels: two smaller arteries which carry blood to the placenta and a larger vein which returns blood to the fetus. It can grow to be 60 cm long, allowing the baby enough cord to safely move around without causing damage to the cord or the placenta. Placenta Abruption When the uterus bleeds from the site where the placenta was attached. The blood typically passes through the cervix and out the vagina. Sometimes, however, the blood remains trapped behind the placenta. Left untreated, placental abruption puts both mother and baby in jeopardy. Placenta Previa The implantation of the placenta at least partially covering the cervix. There are actually three types of previa. Complete previa where the cervical os is completely covered. Partial previa where just a portion of the cervix is covered by the placenta. And the marginal previa that extends just to the edge of the cervix. Partial Placenta Previa The placenta partially covers the internal os. Marginal Previa Transvaginal sagittal view which shows a posterior marginal placenta previa extending about 2 cm over the internal os. Complete Previa Maturity/Grading Placental Grading Based on Placental Calcification 1. Placental Grading Grade 0 No calcifications (to about 31 wk) I Scattered calcifications (31 – 36 wk) II Basal Calcifications (36 – 38 wk) III Basal and interlobar septal calcifications (38 wk to term) 2. The placenta matures considerably after the 40th week. 3. Two parts of the placenta may have different grades, in which the highest grade is assigned. 4. Most term pregnancies have grade I or II placentas. 5. Only about 10% - 15% of term placentas are grade III. Grade 0 Late 1st trimester-early 2nd trimester Uniform moderate echogenicity Smooth chorionic plate without indentations Grade 1 Mid 2nd trimester –early 3rd trimester (~18-29 wks) Subtle indentations of chorionic plate Small, diffuse calcifications (hyperechoic) randomly dispersed in placenta Grade 2 Late 3rd trimester (~30 wks to delivery) Larger indentations along chorionic plate Larger calcifications in a “dot-dash” configuration along the basilar plate Grade 3 39 wks – post dates More irregular calcifications with significant shadowing Placenta Accreta Placenta accreta is a severe obstetric complication involving an abnormal attachment of the placenta to the myometrium. There are three forms of placenta accreta, distinguishable by the depth of penetration. Placenta Accreta The most common form of placenta accreta which is the invasion of the myometrium which does not penetrate the entire thickness of the muscle. Placenta increta occurs when the placenta extends into the muscle of the uterine wall. Placenta percreta, the worst form of the condition is when the placenta penetrates the entire uterine wall. Placenta Accreta Typical image of massive anterior placenta percreta. US Doppler shows the newly formed vessel between uterus and the bladder. Multiple Gestations Diamniotic Diamniotic pregnancy is when there are more than one amniotic sac. Monoamniotic Monoamniotic twins are identical twins who share the same amniotic sac. This very rare condition occurs in an estimated 1 in 25,000 to 1 in 60,000 pregnancies, and historically has resulted in the in-utero death of one or both babies in 50 to 70 percent of cases. Complications of the Fetus and Newborn with Multiple Gestation Preterm births. Compared to singleton pregnancies, a twin is seven times more likely and a triplet is over 20 times more likely to die in the first month of life. Prematurity is associated with an increased risk of respiratory distress syndrome (RDS), intra-cranial hemorrhage, cerebral palsy, blindness, low birth weight, and neonatal morbidity and mortality. Intrauterine growth restriction, intrauterine death of one or more fetuses, miscarriage, and congenital anomalies are all more common. Lifelong disability is over 25% for babies weighing less than 1,000 grams. Maternal Complications Associated with Multiple Gestation Preeclampsia, also called pregnancy-induced hypertension, occurs three to five times more frequently. Premature labor requiring prolonged bed rest or hospitalization is common. Placental abnormalities associated with maternal hemorrhage are more likely to occur. Gestational diabetes, anemia, and polyhydramnios occur more frequently. Cesarean section is often needed for twin pregnancies and almost always required for triplets. Fetal Abnormalities Cranial Abnormalities Hydrocephaly Dilatation of ventricular system secondary to an increase in the amount of CSF. Effects include flattening of parenchyma, intraparenchymal effusions which cause demyelination and brain damage. Cranial Abnormalities Hydranencephaly Total or near total absence of cerebral hemispheres with normally developed meninges and skull. Cerebellum and midbrain, including basal ganglia are intact. 14 weeks shows unfused thalami surrounded by fluid in this fetus with hydranencephaly. Note the lack of cerebral hemispheric tissue. Cranial Abnormalities Holoprosencephaly Abnormality of forebrain diverticulation leading to a single large midline ventricle. Spectrum of pathologic findings include: Alobar: (most severe) large single cavity with minimal amount of cerebral tissue surrounding it, fused thalami, and a facial syndrome. Semilobar: more cerebral tissue present, occipital lobe present. Cranial Abnormalities Porencephaly The presence of cystic areas within the cerebral parenchyma. Cranial Abnormalities Dandy-Walker Syndrome Characterized by: Posterior Fossa Cyst continuous with 4th vent. Posterior fossa enlargement. Cerebellar vermian dysgenesis. Cranial Abnormalities Choroid Plexus Cysts The presence of simple cysts within the choroid plexus. Cranial Abnormalities Microcephaly Small head greater than 3 standard deviations below normal. Cranial Abnormalities Agenesis of Corpus Callosum Absence of the corpus callosum resulting from a chromosomal abnormality or a chromosomal translocation. May be complete or partial. Cranial Abnormalities Intracranial Tumors Rare occurrence. May be cystic, solid, or complex. Facial Abnormalities Facial Clefts Failure of lip fusion, normally complete by 35 days of intrauterine life. Bilateral Cleft Lip Facial Abnormalities Epignathus A teratoma arising from the oral cavity or pharynx. May arise from the sphenoid bone, hard or soft palate, pharynx, tongue or jaw. Neck Abnormalities Cervical Teratoma Similar to epignathus expect the tumor arises from the neck. Neck Abnormalities Nuchal Thickening Increased soft tissue thickness over the posterior aspect of the neck. Neck Abnormalities Cystic Hygroma Benign developmental anomaly of lymphatic origin characterized by single or multiple cystic areas within soft tissues surrounding the neck. Neural Tube Abnormalities Anencephaly Anencephaly, a congenital anomaly in which the cerebral hemispheres and overlying skull and scalp are entirely absent, is the most obvious and dramatic of the “absence” abnormalities.. Note the absence of cranial tissue. Neural Tube Abnormalities Cephalocele/Encephaloceles Protrusions of the meninges and frequently of brain substance through a defect in the cranium. Encephaloceles contain brain tissue and cranial meningoceles do not. Although cephalocele usually result from a defect in neural tube closure, they may be seen in the amniotic band syndrome or in association with various malformation syndromes. Neural Tube Abnormalities Spina Bifida and Meningomyelocele Spina bifida refers to a defect in the spine resulting from a failure of the two halves of the vertebral arch to fuse. These lesions usually occur in the lumbosacral and cervical regions. If the meninges protrude through the defect, the lesion is designated a meningocele; if neural tissue is included, it is a meningomyelocele. No fusions Abdominal Wall Abnormalities Omphalocele Herniation of abdominal viscera into the base of the umbilical cord. May be caused by failure of fusion of the lateral ectomesodermal folds or by persistence of the body stalk in the area normally occupied by the abdominal wall. Abdominal Wall Abnormalities Gastroschisis Smaller herniation of abdominal viscera through an off-midline defect in the abdominal wall, usually located just to the right of the umbilicus. Abdominal Wall Abnormalities Umbilical Cord Hernia Protrusion of a small amount of intestine at the umbilicus. Abdominal Wall Abnormalities Bladder Extrophy Congenital failure of abdominal wall to develop over bladder; urinary bladder may protrude thorough abdominal wall. A 35 week male fetus with bladder extrophy. Genitourinary Abnormalities Ureteropelvic Junction Obstruction Narrowing (stricture) at this junction which reduces the flow of urine from the kidney and can result in enlargement of the kidney caused by the backup of urine into the renal pelvis (hydronephrosis) and kidney damage. UPJ obstruction can be severe, minimal, or intermittent. Postnatal ultrasound confirmed the ureteropelvic junction obstruction. Genitourinary Abnormalities Ureterovesical Junction Obstruction Rare, and is noted by dilatation of the ureter to the level of the bladder. Genitourinary Abnormalities Bladder Outlet Obstruction Bladder outlet obstruction occurs at the base of the bladder, and reduces or prevents the flow of urine into the urethra. Keyhole Appearance Genitourinary Abnormalities Posterior Urethral Valves Predominantly a male abnormality because of redundant membranous folds in the posterior urethra that lead to varying degrees of GU system obstruction. Axial ultrasound image depicts a massively distended bladder with a keyhole appearance posteriorly. Gastrointestinal Abnormalities Esophageal Atresia Esophageal Atresia is a disorder of the digestive system in which the esophagus does not develop properly. The disorder is a congenital defect, which means it occurs before birth. Gastrointestinal Abnormalities Midgut Volvulus Midgut volvulus refers to twisting of the entire midgut about the axis of the superior mesenteric artery. Gastrointestinal Abnormalities Duodenal Atresia Duodenal atresia is due to the failure of canalization of the embryonic duodenum. 35 week fetus demonstrating the "double bubble" sign characteristic of duodenal atresia. Skeletal Abnormalities Achondrogenesis A rare, lethal form of short-limbed dysplasia. It is the failure of ossification process. Two Types: Type I (Parenti-Fraccaro) • Absent vertebral ossification centers • Incomplete ossification of skull • Rib fractures • Arms extremely short and stubby • Head not enlarged compared to trunk Note the absent ossification of the skull. Type II (Langer-Saldino) • Head large compared to body • Prominent skin folds over a short neck • Small chest • Distended abdomen and possible fetal hydrops • Very short limbs held away from body Short arm does not reach the anterior midline. Skeletal Abnormalities Homozygous Dominant Achondroplasia A lethal, short limbed dysplasia characterized by rhizomelic dwarfism, limb bowling, lordotic spine and a bulky head. It occurs in fetuses in which both parents are achondroplastic dwarfs. Cloverleaf Skull Skeletal Abnormalities Thanatophoric Dysplasia Lethal skeletal dysplasia characterized by extreme rhizomelia (shortening of the proximal segment of an extremity), bowed long bones, narrow thorax with normal trunk length, a relatively large head, and severely flattened vertebral bodies. Thorax is narrow and respiratory distress usually follows birth leading to death. Fig. 1. Thanatophoric dysplasia in a 21-week fetus. A. Demonstrates a cloverleaf-like skull. B. Rhizomelic micromelia with bowing of the humerus is apparent (arrows). The skin appears thick because of extreme redundancy Skeletal Abnormalities Campomelic Dysplasia A skeletal dysplasia characterized by bent or bowed limbs. Femoral bone deformity. Skeletal Abnormalities Short-Rib Polydactyly Syndrome A lethal dysplasia characterized by polydactyly and an extremely narrowed thorax. Fig. 5. Short-rib dysplasia with polydactyly in a 21-week fetus. A. Sagittal image shows a narrow thorax and relatively protuberant abdomen (arrows). B. There is an extra digit (6) lateral to the fifth finger. C, D. Autopsy photographs show a narrow thorax with short ribs, a protuberant abdomen, micromelia, and postaxial polydactyly (arrow). Skeletal Abnormalities Osteogenesis Imperfecta Disorder production, secretion or function of collagen. Abnormal fragility of bone caused by hypomineralization. Axial scan of fetal head, demonstrating poor ossification of the skull and easy compression of the calvarium. Skeletal Abnormalities Hypophosphatasia A bony demineralization disorder resulting from low levels of serum and tissue alkaline phosphate. Skeletal Abnormalities Talipes Equinovarus (Club Foot) Inversion of the foot and flexion of the sole. Skeletal Abnormalities Sirenomelia (Mermaid Syndrome) Lower extremity fusion which is a severe manifestation of caudal regression syndrome. Cardiac Abnormalities Atrial Septal Defect and Ventricular Septal Defects ASD - Any abnormal opening between the atria. VSD - Caused by incomplete closure of interventricular foramen and failure of the membranous part of IV septum. Ventricular and Atrial Septal Defects. This is a hole in the wall that separates the two ventricular and atrial chambers. This is also known as an endocardial cushion defect or an AV canal defect. When this is present the risk for Down syndrome is 50%. Cardiac Abnormalities Transposition of the Great Arteries The origin of the great vessels are transposed so that the aorta arises from right ventricle and pulmonary trunk arises from the left ventricle. Cardiac Abnormalities Ectopic Cordis All or part of heart is located outside of chest cavity. Transverse scan demonstrating ectopic 4 chamber view of the heart (right) Coexisting Disorders Leiomyoma Leiomyomas or uterine fibroids are benign tumors of the uterus. Leiomyomas arise from the overgrowth of smooth muscle and connective tissue in the uterus. The uterus appears enlarged and shows the presence of a large hypoechoic mass in the region of the lower uterine body and uterine cervix. Gestational Trophoblastic Disease A designation given to several disorders arising from either normal or abnormal fertilization of an ovum, resulting in neoplastic changes in the trophoblastic elements of the developing blastocysts. GTD is classified into hydatidform mole, nonmetastatic disease or invasive mole; and metastatic disease or choriocarcinoma. Hydatidform Mole Myometrial Contraction Throughout the pregnancy, focal areas of smooth muscle in the uterine wall contract, causing a bulging into the amniotic cavity. Placenta appears to become thicker due to a focal myometrial contraction.