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SON 2122 Obstetrical Sonography II Chapter 15 The Fetal Abdominal Wall and GI system Harry H. Holdorf PhD, MPA, RDMS, RVT, LRT Outline GASTROSCHISIS – Abdominal Wall OMPHALOCELE – Abdominal Wall Bladder Extrophy – Abdominal Wall Congenital Diaphragmatic Hernia – Abdominal Wall Abdominal Ascites – Abdominal Wall Persistent right umbilical vein – Abdominal Wall Diaphragm – Abdominal wall GASTROINTESTINAL ATRESIA Esophageal atresia Duodenal Atresia Intestinal Atresia Meconium Peritonitis Teratomas Meconium Ileus Volvulus The Gastro-Intestinal System Esophagus Difficult to image unless fetus is swallowing Stomach On transverse view, seen ovoid or round fluid collection in upper left abdomen Muscular layer may be thickened in hypertrophic pyloric stenosis Normal fetal esophagus The fetal Stomach GASTROSCHISIS Protrusion of intestines into the amniotic cavity through an open defect in the anterior abdominal wall. Gastroschisis occurs adjacent to the cord insertion, usually on the right. It is not covered by a membrane. It results from a muscular defect, possibly related to vascular disruption. Gastroschisis is not associated with an increased risk of chromosomal abnormalities. Gastroschisis Gastroschisis Sonographic findings. Loops of bowel seen extending into the amniotic cavity Cord is seen adjacent to the defect No membranous sac covers the hernia OMPHALOCELE Results from a failure of the intestines to return to the abdomen during the second stage of intestinal rotation. They may contain a single loop of bowel, or most of the abdominal contents, depending on the severity. The defect is covered by a layer of amniotic epithelium, and is seen at the level of the umbilical cord insertion. Rupture of the sac during vaginal delivery may cause sepsis. There is a high association between omphalocele and other congenital anomalies (65-90% of fetuses seen have a cardiac defect or chromosomal abnormities, most commonly Trisomies 13 and 18), patients should receive genetic counseling. Sonographic findings Extra-abdominal mass, consisting of a combination of fluid-filled bowel loops, mesentery, omentum, liver, and sometimes pancreas and spleen Mass contiguous with umbilical cord Membranous sac covers the herniated organs Omphalocele Omphalocele Bladder Extrophy This midline defect involves the lower abdominal wall as well as the anterior wall of the urinary bladder. Generally, bladder extrophy is an isolated defect, but can possibly be associated with genital anomalies such as cleft clitoris, epispadias, and the wide separation of pubic bones. Midline defect involves the lower abdominal wall as well as the anterior wall of the urinary bladder. Isolated defect Protrusion of the urinary bladder Possibly associated with genial anomalies – cleft clitoris, or wide separation of public bones Bladder not ID over 30 minutes of scanning, but normal fluid Possible soft tissue protrusion form lower abdominal wall Separation of pubic bones EPISPADIAS: Epispadias is a rare defect that is present at birth (congenital). It is located at the opening of the urethra. In this condition, the urethra does not develop into a full tube. The urine exits the body from the wrong place. Epispadias can occur with bladder exstrophy. In this rare birth defect, the bladder is inside out and sticks through the abdomen wall. Epispadias can also occur with other birth defects. Epispadias occurs in 1 out of every 117,000 newborn boys and 1 in 484,000 newborn girls. The condition is usually diagnosed at birth or soon afterward. Patients who have more than a mild case of epispadias will need surgery. Some people with this condition may continue to have urinary incontinence, even after surgery. Ureter and kidney damage and infertility may occur. Sonographic findings Bladder not identified over 30 minutes of scanning but normal AFV Possible soft tissue protrusion from lower abdominal wall Separation of pubic bones (diastasis) Micorphallus in male fetus Bladder Extrophy-The cord insertion is visualized above the protruding mass that contains bladder and bowel loops. Congenital Diaphragmatic Hernia CDH is the most common developmental abnormality of the diaphragm. The small bowel, stomach, spleen, colon and liver may herniated into the chest. Hernias usually occur on the left side 80% of the time and are associated with pulmonary hypoplasia if large. Cardiomedastinal shift is the most recognizable sonographic feature. The Sonographer should be aware of CDH associations with other anomalies, frequently cardiac and brain. CDH is common Small bowl, stomach, spleen colon and liver may herniate into the chest. Usually occur on the left side (80%) and associated with pulmonary hypoplasia if large Cardio-mediastinal shift can occur Associated with other anomalies ID of fluid-filled bowel and stomach within the thoracic cavity at level of 4 chamber view of heart Heart displaced from the left chest toward the right Associated Polyhydramnios Sonographic findings ID of fluid-filled bowel and especially stomach within the thoracic cavity at the level of the four chamber view of the heart Heart displaced from the left chest toward the right Associated Polyhydramnios CDH (Congenital Diaphragmatic Hernia) CDH Abdominal Ascites Ascites in the fetal abdomen is most commonly associated with a condition called Hydrops Fetalis. Abdominal Ascites Persistent right umbilical vein When the umbilical vein courses toward the left side of the fetal abdomen, this is called persistent right umbilical vein. The umbilical vein is actually entering the right portal vein of the liver rather than the left portal vein. This variation itself is not pathogenic, but can be seen with some anomalous conditions, and therefore warrants a detailed investigation for other fetal anomalies. PRUV PRUV-Transverse color Doppler scan of the abdomen demonstrating the right umbilical vein (pointing towards the stomach). Diaphragm Appears as a hypoechoic curved line separating the more echogenic fetal lungs from the liver and the stomach Diaphragm GASTROINTESTINAL ATRESIA Esophageal atresia This is the discontinuation of the esophagus. 90% are accompanied by a distal trachoesophageal fistula. There is a 30-70% association with other congenital malformations, including cardiovascular, gastrointestinal, genitourinary, and musculoskeletal anomalies. Discontinuation of the esophagus. 70% have other malformations Small or absent fluid-filled stomach Failure to demonstrate the stomach on serial sonograms Polyhydramnios Esophogeal Atresia Sonographic Findings Small to absent fluid-filled stomach Failure to demonstrate stomach on serial sonograms Associated Polyhydramnios Not always detectable with ultrasound Esophageal atresia is a congenital medical condition which affects the alimentary tract. It causes the esophagus to end in a blind-ended pouch rather than connecting normally to the stomach. It occurs in approximately 1 in 4425 live births. Congenital esophageal atresia (EA) represents a failure of the esophagus to develop as a continuous passage. Instead, it ends as a blind pouch. Tracheoesophageal fistula (TEF) represents an abnormal opening between the trachea and esophagus. EA and TEF can occur separately or together. EA and TEF are diagnosed in the ICU at birth and treated immediately. This condition takes several different forms, often involving one or more fistulas connecting the trachea to the esophagus (tracheoesophageal fistula). This birth defect arises in the fourth fetal week, when the trachea and esophagus should begin to separate from each other. Associations Other birth defects may co-exist, particularly in the heart, but sometimes also in the anus, spinal column, or kidneys. This is known as VACTERL syndrome because of the involvement of Vertebral column, Anorectal, Cardiac, Tracheal, Esophageal, Renal, and Limbs. It is associated with polyhydramnios in the third trimester. Diagnosis This condition is visible, after about 26 weeks or it may be detected soon after birth as the affected infant will be unable to swallow its own saliva. Also, the newborn can present with gastric distention, cough, apnea, and cyanosis Any attempt at feeding could cause aspiration pneumonia as the milk collects in the blind pouch and overflows into the trachea and lungs. Furthermore, a fistula between the lower esophagus and trachea may allow stomach acid to flow into the lungs and cause damage. Because of these dangers, the condition must be treated as soon as possible after birth. Esophageal Atresia Duodenal Atresia This is the most common perinatal intestinal obstruction. Causes include failure of normal embryonic development, choledochal cysts, superior mesenteric artery defect, and extrinsic pressure. 65% of fetuses with duodenal atresia have a karyotype abnormality or an associated malformation at birth, most commonly cardiac and vertebral anomalies. 30% of infants with DA have Down syndrome. Duodenal atresia is the congenital absence or complete closure of a portion of the lumen of the duodenum. Approximately 20-40% of all infants with duodenal atresia have Down syndrome Approximately 8% all infants with Down syndrome have duodenal atresia. It is also associated with polyhydramnios. The diagnosis of duodenal atresia is usually be ultrasound of the abdomen, which shows two large air filled spaces, the so-called "double bubble" sign The air is trapped in the stomach and duodenum. Since the closure of the duodenum is complete in duodenal atresia, no air is seen distal to the duodenum. Duodenal Atresia Most common perinatal intestinal obstruction 30% have Down’s syndrome Double bubble sign- distention of the stomach and first portion of the duodenum Polyhydramnios Sonographic Findings “Double bubble sign” due to simultaneous distention of stomach and first portion of the duodenum Polyhydramnios Duodenal Atresia Duodenal Atresia Intestines Normally mixed echogenicity to cystic in appearance. Peristalsis should be seen by late second trimester. Meconium – a mixture of bile and swallowed vernix, epithelium, and fetal hair, becomes packed in the large bowel and may appear as highly echogenic areas within the bowel. Intestinal Atresia Obstruction of the intestine, with subsequent distention of bowel loops, may occur anywhere along the intestinal tract or at the level of the anus. The precise site is frequently indeterminate. Intestinal Atresia Obstruction of the intestine Distention of bowel loops Multiple fluid-filled bowel loops Increased bowel peristalsis Possible perforation – indicated by abdominal calcifications and ascites Polyhydramnios Intestinal atresia is a malformation where there is a narrowing or absence of a portion of the intestine. This defect can either occur in the small or large intestine. The different types of intestinal atresia are named after their location: Duodenal atresia - malformation of the duodenum, part of the intestine that empties from the stomach Jejunal atresia - malformation of the jejunum, the second part of the intestine extending from the duodenum to the ileum Ileal atresia - malformation of the ileum, the lower part of the small intestine Colon atresia - malformation of the colon Intestinal atresias are often discovered before birth: either by ultrasounds show a dilated intestinal segment due to the blockage, or by the development of polyhydramnios These abnormalities are indications that the fetus may have a bowel obstruction Some fetuses with bowel obstruction have abnormal chromosomes. An amniocentesis is recommended because it can determine not only the sex of the baby, but whether or not there is a problem with the chromosomes. Fetal and neonatal intestinal atresia treated with using laparotomy after birth. If the area affected is small, the surgeon may be able to remove the damaged portion and join the intestine back together. In instances where the narrowing is longer, or the area is damaged and cannot be used for period of time, a temporary stoma may be placed. Sonographic findings Multiple fluid-filled bowel loops Small bowel internal diameter >7mm Increased bowel peristalsis Possible perforation, indicated by abdominal calcifications and ascites Polyhydramnios Often difficult to determine exact site of obstruction Intestinal Atresia Intestinal Atresia Meconium Peritonitis Peritoneal inflammatory reaction occurs following an intrauterine bowel perforation. Perforation may occur after the fetal bowel obstruction caused by intestinal atresia, volvulus, or Meconium ileus. Cystic fibrosis is considered to be the etiology in 30-40% of all patients because of thick, sticky Meconium. Meconium Peritonitis Peritoneal inflammatory reaction following an intrauterine bowel perforation. Cystic fibrosis is a likely etiology because of thick, sticky Meconium. Brightly echogenic, intra-abdominal foci Meconium peritonitis refers to rupture of the bowel prior to birth, resulting in fetal stool (meconium) escaping into the surrounding space (peritoneum) leading to inflammation (peritonitis). Despite the bowel rupture, many infants born after meconium peritonitis in utero have normal bowels and have no further issues. Twenty percent of infants born with meconium peritonitis will have vomiting and dilated bowels on x-rays which necessitates surgery. Meconium peritonitis is often diagnosed on prenatal ultrasound where it appears as calcifications within the peritoneum. Infants with cystic fibrosis are at increased risk for meconium peritonitis. Sonographic findings Brightly echogenic, intra-abdominal foci which cast an acoustic shadow Fetal ascites and Polyhydramnios Meconium Peritonitis Meconium Peritonitis-Calcifications are seen throughout the abdomen in this 17 week fetus with meconium peritonitis Teratomas Usually arises from the sacral area. Three pathologic types exist: Mature, immature and malignant. They frequently are hypervascular and consists of solid and calcified components They are described by the site of origin: Pre-sacral Sacrococcygeal Teratomas Germ cell tumors usually arising from the sacral area Complex, large mass seen in the fetal pelvis or arising from the fetal rump. May contain cystic, solid, and calcified components Sonographic findings A complex, large mass seen in the fetal pelvis of arising from the fetal rump May contain cystic, solid, and calcific components Possible differential diagnosis includes Myelomeningocele Teratomas Teratomas Meconium ileus Sometimes the meconium becomes thickened and congested in the ileum, a condition known as meconium ileus. Meconium ileus is often the first symptom of cystic fibrosis. In cystic fibrosis, the meconium can form a blackgreen mechanical obstruction in a segment of the ileum. Beyond this there may be a few separate grey-white globular pellets. Below this level, the bowel is a narrow and empty micro-colon. Above the level of the obstruction, there are several loops of hypertrophied bowel distended with fluid. No meconium is passed, and abdominal distension and vomiting appear soon after birth. About 20% of cases of cystic fibrosis present with meconium ileus, while approximately 20% of one series of cases of meconium ileus did not have cystic fibrosis. The presence of meconium ileus is not related to the severity of the cystic fibrosis. The obstruction can be relieved. Meconium ileus volvulus A volvulus is a loop of the bowel whose nose has twisted on itself. The American Heritage Stedman's Medical Dictionary defines volvulus slightly differently as "abnormal twisting of the intestine causing obstruction," which adds obstruction in the definition, and would be the more clinically significant term. Midgut volvulus occurs in patients (usually in infants) that are predisposed because of congenital intestinal malrotation Segmental volvulus occurs in patients of any age, usually with a predisposition because of abnormal intestinal contents (e.g. meconium ileus) or adhesions. Volvulus of the cecum, transverse colon, or sigmoid colon occurs, usually in adults, with only minor predisposing factors such as redundant (excess, inadequately supported) intestinal tissue and constipation. Regardless of cause, volvulus causes symptoms by two mechanisms. One is bowel obstruction, manifested as abdominal distension and vomiting. The other is ischemia (loss of blood flow) to the affected portion of intestine. This causes severe pain and progressive injury to the intestinal wall, with accumulation of gas and fluid in the portion of the bowel obstructed. Ultimately, this can result in necrosis of the affected intestinal wall, acidosis, and death. Acute volvulus therefore requires immediate surgical intervention to untwist the affected segment of bowel and possibly resect any unsalvageable portion. volvulus Homework List all abnormalities and conditions with which Oligohydramnios is associated. Polyhydramnios is associated with many conditions. List as many as you can. Define premature rupture of membranes (PROM) What are the sonographic fetal findings in a patient with PROM? What are three distinctive features of gastroschisis? What are three distinctive features of omphalocele? What is bladder Exstrophy? What sonographic findings might suggest bladder Exstrophy? What is the most recognizable sonographic feature of a congenital diaphragmatic hernia (CDH)? List other sonographic findings of CDH, as well as possible associated anomalies. True or false: Esophageal atresia is very commonly accompanied by a distal trachoesophageal (T-E) atresia. List the sonographic findings of esophageal atresia. Describe how duodenal atresia may appear sonographically. What other anomalies are associated with duodenal atresia? Intestinal atresia may occur anywhere along the intestinal tract, and often the site of obstruction is indeterminate. What are the sonographic findings of an intestinal atresia (other than duodenal atresia?? What is Meconium peritonitis? What findings might raise suspicion for Meconium peritonitis in a fetus? Take home test 1. In the late gestation, the hypoechoic contents of the fetal colon typically represent Normal muscle of the bowel Meconium A distal obstruction, such as anal atresia An inflammatory reaction to bowel perforation 2. With endovaginal scanning, a small soft tissue mass is seen anterior to the abdominal wall of an 11 week embryo, at the location of the umbilical cord insertion. What is the probable explanation for this finding? Early diagnosis of an omphalocele Early diagnosis of a gastroschisis Normal herniated bowel in the umbilical cord Amniotic band syndrome causing evisceration 3. The fetal urinary bladder is not observed at the beginning of the obstetrical sonogram. The Sonographer should Consider a diagnosis of bilateral renal agenesis Search carefully for associated cardiac anomalies Continue with the rest of the exam, and re-check for bladder filling after 20-30 minutes Try a higher frequency transducer for better image resolution. 4. Which of the following statements regarding diaphragmatic hernias is not true? Most diaphragmatic hernias occur on the right side A differential diagnosis for a fluid-filled mass on the lung is CCAM type I Severe diaphragmatic hernias include bowel and even liver There is associated Polyhydramnios with a diaphragmatic hernia 5. An omphalocele defect, in addition to ectopic cordis, is associated with Meckel-Gruber syndrome Pentalogy of Cantrell Fetal alcohol syndrome Edward’s syndrome 6. Duodenal atresia is characterized by which of the following sonographic findings? Oligohydramnios Multiple fluid-filled structures in the fetal abdomen Failure to demonstrate the stomach on two consecutive exams Polyhydramnios More Homework From Callen 1. What are the consequences of the failure to visualize the fetal stomach? 2. What are the consequences of an Esophageal Atresia? 3. Why would you, as a sonographer, be concerned that your fetal exam patient demonstrated echogenic small bowel? 4. What sign would be expected in a fetus with duodenal atresia? Explain your answer- what do the findings represent? Callen… 5. Define and give the ramifications of Meconium peritonitis. What are the causes? What is the prognosis of the fetus diagnosed with this? What is the US finding? 6. Explain the anomaly of Persistent Right Umbilical Vein. 7. Define Umbilical Vein Varix 8. List the causes of fetal splenomegaly 9. Is the differential diagnosis for cystic abdominal mass different between the male and female fetus? Explain Callen: 10. Explain the embryonic development of the fetal gastrointestinal tract (the fetal gut). 11. Define Cloacal Exstrophy 12. Define Limb-Body Complex 13. Explain the importance of the relationship of the cord insertion to an abdominal wall defect. 14. Define Uterine Synechia
