, Cord, & Fluid Abruption Accreta/Increta/Percreta Chorioangioma Complete Partial Not generally Relevant to U/S Gestational Age (Weeks) Distance from 16-23.9 24 to Internal Os >20 mm No No 11-20 mm 0-10 mm covers os Complete Gestational Age (Weeks) Distance from 16-23.9 24 to Internal Os >20 mm No No 11-20 mm 0-10 mm covers os Complete 1
Gestational Age (Weeks) Distance from 16-23.9 24 to Internal Os Gestational Age (Weeks) Distance from 16-23.9 24 to Internal Os >20 mm No No >20 mm No No 11-20 mm 0-10 mm covers os Complete l edge Cervical os 11-20 mm 0-10 mm covers os Complete Gestational Age (Weeks) Distance from 16-23.9 24 to Internal Os >20 mm No No 11-20 mm 0-10 mm covers os Complete Pitfall Fetal Presenting Part Obscuring Lower Uterine Segment Fetal presenting part (especially head) may shadow out part of the cervix or lower uterine segment, leading to inability to diagnose or exclude Is There a? Question Answered by Manually Lifting Fetal Head Medina & Kibathi: Lifting head to R/O No Pitfall Overly Full Maternal Bladder Overly full bladder may push together the anterior & posterior walls of the lower uterine segment, simulating the cervix & leading to false positive diagnosis of placenta 2
Pseudo Due to Overfilled Maternal Bladder Lower segment simulating cervix Wilkins: Pseudo Bladder full? Bladder emptied Pitfall Lower Uterine Segment Contraction Contraction in the lower uterus distorts the lower uterine segment, & can cause false positive diagnosis of placenta Lower Segment Uterine Contraction Does Not Permit Assessment for Portillo & Soto?? Contraction resolved: No Contraction resolved: Sonographic Approach to Diagnosis of Scan Transabdominally Through Partially Full Bladder Fetus obscures lower uterine segment Manually Lift Head Unable to lift head Scan Translabially Cervix/lower segment obscured by gas Scan Transvaginally l Abruption Ultrasound Appearances Abruption: Retroplacental Hematoma Retroplacental Hematoma Submembranous Hematoma Osborne: Abruption Hematoma Normal Sonogram 3
Hematoma Abruption: Submembranous Hematoma l Abruption Pitfall Isoechoic Hematoma King: Abruption Hypoechoic hematoma can be mistaken for placenta, leading one to miss an abruption Abruption with Isoechoic Hematoma l Abruption Ghattas: Abruption w isoechoic hematoma 5 days later Pitfall Uterine Contraction Uterine contraction under the placenta can simulate a hematoma, thereby leading to false positive diagnosis of placental abruption Uterine Contraction Simulating Abruption Ripley: contraction simulating abruption? Abruption Accreta/Increta/Percreta Abnormal Adherence of to Myometrium Percreta: penetration of villi through myometrium Increta: invasion of chorionic villi into myometrium Accreta: abnormal adherence without invasion of villi Contraction Contraction resolved 4
Accreta/Increta/Percreta Cause Partial or complete absence of decidua basalis direct attachment of placenta to myometrium Often occurs when placenta implants at site of damaged endometrium (e.g., Cesarean scar) Complications Difficulty removing placenta after delivery Bleeding at delivery may necessitate hysterectomy Uterine rupture (increta/percreta) Internal hemorrhage (percreta) Accreta/Increta/Percreta Relationship to Prior Cesarean Section Prior Cesarean Section(s) + Risk of Ac-/In-/Percreta # Prior Risk of Accreta if Cesarean Sections Patient has * 0 5% 1 24% 2 48% * Clark et al, OB GYN 1985 Accreta/Increta/Percreta U/S Findings Accreta Confirmed by Pathology After Gravid Hysterectomy ** Anterior /low-lying placenta in woman with prior Cesarean section(s) *** Above + thin myometrium ( 2 mm) overlying placenta Schiffman: Increta **** extends thru uterine wall (e.g., into bladder) * Large, irregular placental venous lakes Percreta Path-Proven S/P Hysterectomy Truglia: Percreta Smith & Lewis Accreta in Fundus Normal Comparison 5
l Chorioangioma l Chorioangioma Benign tumor of the placenta Reported incidence 0.5-1% Generally of no clinical significance Occasional complications have been reported: Polyhydramnios Fetal thrombocytopenia Fetal hemolytic anemia Intrauterine growth restriction Leitner l Chorioangioma Umbilical Cord Montoriol Umbilical Cord Umbilical Cord Structure: 3VC (2 UA s) vs. 2VC (1 UA) Structure Doppler l t l insertion Vasa Prolapsed/presenting Cord entanglement in monoamniotic twins Nuchal 3VC 2VC 6
Umbilical Cord Structure: 3VC (2 UA s) vs. 2VC (1 UA) Single Umbilical Artery (2-Vessel Cord) 3VC 2VC Most common structural anomaly of the umbilical l cord Occurs in 0.2-1% of singletons, 6-11% of twins ~30% of fetuses with SUA have structural anomalies or aneuploidy Umbilical Cord Cysts Umbilical Cord Cyst May be seen in any trimester Associated with fetal anomalies Omphalocele, cardiac, renal, Often multiple Associated with aneuploidy Umbilical Vein Varix Umbilical Vein Varix May occur within the fetal abdomen or in the umbilical cord Elevated risk of: Structural anomalies Aneuploidy Hydrops Fetal demise 7
Umbilical Cord Insertions into Umbilical Cord Insertions into Velamentous Normal Vasa Vasa Velamentous Cord Insertion, with Vessels in Membranes over Cervix Or Succenturiate Lobe Connected to Main via Vessels in Membranes over Cervix Complications Tearing of vessel during (or prior to) delivery fetal hemorrhage In severe cases: fetal exsanguination death U/S Diagnosis Vessel over cervix with fetal heart rate If unsure whether it is umbilical cord overlying cervix: repeat U/S at a later time Note: Vasa diagnosed in 2nd may resolve by term Vasa Young: vasa Umbilical Cord Presentation & Prolapse Cord presentation: loop of cord lies below the presenting part of the fetus in the presence of intact membranes Often resolves prior to labor, but can lead to cord prolapse Cord prolapse: umbilical cord protrudes through ruptured membranes into the vagina (usually during labour) May lead to fetal hypoxia fetal morbidity/mortality 8
Prolapsed Umbilical Cord Israel: prolapsed cord Sonography of Amniotic Fluid Amniotic Fluid Source & Regulation Amniotic Fluid Regulation 16 Weeks Onward Up to ~16 weeks Diffusion of fluid through membranes, placenta, umbilical cord, fetal skin ~16 weeks onward Production Fetal Urination Cosumption Fetal swallowing & GI absorption Fetal lung absorption Production Consumption Amniotic Fluid Volume Determined by Dye-Dilution Amniotic Fluid in the First Trimester GA (weeks) Median AFV (ml)* 10 30 15 150 20 400 25 675 30 900 35 950 40 700 42 500 * Brace et al, Am J Obstet Gynecol 1989; 161: 382-8 Early 1 st Trimester Mid-Late 1 st Trimester 9
Amniotic Fluid in the 1 st Trimester Sonography of Amniotic Fluid 2 nd & 3 rd Trimesters 6 7 8 9 Amniotic fluid echogenicity Amniotic fluid volume Methods of assessment Evaluation of polyhydramnios & oligohydramnios 10 11 12 weeks Echogenic Amniotic Fluid Etiologies Physiologic Vernix Pathologic Blood Meconium Purulent fluid (chorioamnionitis) Should we ever worry when we see echogenic amniotic fliud? Echogenic Amniotic Fluid Should We Ever Worry? In the 3 rd trimester, echogenic fluid is due to vernix in 90% of cases* Assume vernix unless strong clinical suspicion of blood, meconium, or infection In the 2 nd trimester, consider pathologic cause (especially if the fluid is very echogenic) * Sherer et al, Obstet Gyn 1991; 78: 819-822 Brown et al, J US Med 1994; 13: 95-97 Echogenic Amniotic Fluid in the 2 nd Trimester Echogenic Amniotic Fluid in the 3 rd Trimester 21 weeks: Chorioamnionitis in 1 twin s sac (proven by amnio) 18 weeks: Blood in amniotic fluid (Presumed: patient was bleeding) 25 weeks 37 weeks Assumed to be vernix (unless strong clinical suspicion of blood, meconium, or infection) 10
Amniotic Fluid in the 2 nd & 3 rd Trimesters Volume (Poly- & Oligohydramnios) AIUM Guidelines for 2 nd & 3 rd Trimester Obstetrical Ultrasound A qualitative or semiquantitative estimate of amniotic fluid volume should be reported. Comment Although it is acceptable for experienced examiners to qualitatively estimate amniotic fluid volume, semiquantitative methods have also been described for this purpose (e.g., amniotic fluid index, single deepest pocket, 2-diameter pocket). Amniotic Fluid Volume Sonographic Assessment Normal Amniotic Fluid Volume (19 weeks) Subjective assessment Single-deepest-pocket pocket measurement <1-2 cm = oligohydramnios >8 cm = polyhydramnios Amniotic fluid index (AFI): Sum of deepest pockets in 4 quadrants <5 cm = oligohydramnios >18-20 cm = polyhydramnios Brydges & Hosking: Normal AFI Subjective Assessment AFI = 4.5 + 2.7 + 2.6 + 2.6 = 12.4 Oligohydramnios (32 weeks) Polyhydramnios (30 weeks) Lieberman: Elevated AFI Dong: Oligo Subjective Assessment Subjective Assessment AFI = 1.2 + 0 + 3.0 + 0 = 4.2 AFI = 9.4 + 10.0 + 9.6 + 8.5 = 37.5 11
Subjective Assessment Quick & efficient Accounts for gestational age variations in amniotic fluid volume? Reliable with inexperienced operator Note: Best documented with video clip Single Deepest Pocket or Amniotic Fluid Index Simple & quick Even with oligohydramnios, one or more deep pockets may be found in crevices (e.g., neck) AFI May be affected by fetal movement Same Height Not mathematically valid: Different Volume Linear measurement Volume Amniotic Fluid Volume Assessment Which Method? Amniotic Fluid Volume Assessment Which Method? Published studies* using dye-dilution as gold standard find: No significant difference between subjective assessment & AFI Neither is accurate at Dx ing or fluid volume * Magann et al, J Clin Ultrasound 1997; 25: 249-253 * Magann et al, J Ultrasound Med 2001; 20: 191-195 Either subjective assessment or amniotic fluid index is acceptable 12