CLOACAL EXSTROPHY

Cloacal extrophy is a severe disruption of the urogenital tract resulting in a central extrophic bowel field flanked by two hemibladders (each having a urethral orifice). The bowel field has three or four orifices (anterior prolapsed terminal ileum resulting in an "elephant trunk" appearance; a distal orifice leading to a blind ending distal colon; one or two appendiceal orifices) (1).

• 1:250,000 live births (2).
• Occurs more frequently in twins (3-5).
• No reported association with chromosomal abnormalities.

PATHOGENESIS

Link to Pathogenesis

ULTRASOUND (5)

• Omphalocele.
• Spinal segmentation disorders (40-90%) (1).
• Absent bladder (in the presence of visible renal parenchyma). . Color Doppler imaging to correctly identify both umbilical arteries is an important diagnostic tool for localization of the bladder in the lower fetal abdomen
• Protruding mass - the mass does not contain any large cystic areas as it does not contain the urine that is excreted directly from the ureters into the amniotic fluid
• Lumbosacral meningomyelocele (30-70%) (1).
• Lower extremity malformations including clubfoot or other deformities of the long bones (20-45%) (1).
• Renal anomalies include unilateral or bilateral renal agenesis (10-35%), crossed fused renal ectopia (10-60%) (1).
• Gastrointestinal malformations include malrotation, duplication or anatomically short small bowel (50% of cases).
• Ascites (6). This is explained by the escape of fluid from the bladder or urethra into the vagina, fallopian tubes and ultimately into the peritoneal cavity.
• A single umbilical artery may be present.
• Ambiguous genitalia are important findings and visualization of normal external genitalia will probably exclude the diagnosis of bladder or cloacal exstrophy.
• Cloacal dysgenesis sequence – this represents the association of imperforate anus with confluence of the rectum, vagina and bladder in a urogenital sinus. This usually occurs sporadically but has been associated with chromosomal anomalies (7). The appearance is dependent on the gestational age of the fetus (8,9):
• In the first trimester there is usually dilated loops of bowel, then megacystis, ascites and oligo or anhydramnios when no external openings are present.
• In the second and third trimester there is a pelvic fluid-filled structure (appearance is dependent on the age of the fetus and the level of bowel involvement). The perineum lacks anal, urethral and vaginal openings and the labia minora and majora may be absent in females and the scrotum and penis hypoplastic or absent in males (10,11).

ASSOCIATED ANOMALIES

ASSOCIATED ANOMALIES

OEIS syndrome

Link to OEIS syndrome

• Omphalocele (70-90%)
• Exstrophy of the cloaca
• Imperforated anus
• Spinal abnormalities

Vertebral anomalies (46%)

• Sacralization of L5
• Congenital scoliosis
• Sacral agenesis
• Interpedicular widening

Upper urinary tract (42%)

• Pelvic kidney
• Horseshoe kidney
• Hypoplastic kidney
• Solitary kidney.

Gastrointestinal

• Malrotation (30%)
• Double appendix (30%)
• Absent appendix (21%)
• Short small bowel (19%)
• Small bowel atresia (5%)
• Abdominal musculature deficiency (1%)

Cardiovascular

Central nervous system

Single umbilical artery

DIFFERENTIAL DIAGNOSIS

• Cloacal extrophy must be distinguished from amniotic band syndrome and limb-body wall complex. Aberrant sheets or bands, asymmetric encephalocele, anencephaly or exencephaly, bizarre clefting patterns and multiple amputations are not generally present in cloacal extrophy and should help distinguish the conditions.

REFERENCES

1. Richards DS, Langham MR, Mahaffey SM. The prenatal ultrasonographic diagnosis of cloacal exstrophy. J Ultrasound Med 1992;11:507-510.
2. Carey JC, Greenbaum B, Hall DH. The OEIS complex. Orig Art Ser 1978;14:253.
3. Redman JF, Seibert JJ, Page BC. Cloacal exstrophy in identical twins. Urology 1981;17:73.
4. Lowry R, Baird P. Familial gastroschisis and omphalocele. Am J Hum Genet 1982;34:517.
5. Chitrit Y, Zorn B, Filidori M et.al. Cloacal exstrophy in monozygotic twins detected through antenatal screening. J Clin Ultrasound 1993;21:339-342.
6. Cilento BG, Benacerraf BR, Mandell J. Prenatal diagnosis of cloacal malformation. Urology 1994;43(3):386-388.
7. Chen CP, Chern SR, Lee CC et.al. Isochrome 18q in a fetus with congenital megacystis, IUGR and cloacal dysgenesis sequence. Prenat Diagn 1998;18:1068-1074.
8. Zaccara A, Gatti C, Silveri M et.al. Persistent cloaca: are we ready for a correct prenatal diagnosis? Urology 1999;54:367.
9. Cacciaguerra S, Lo Peresti L, DiLeo L et.al. Prenatal diagnosis of cloacal anomaly. Scand J Urol Nephrol 1998;32:77-80.
10. Liang X, Ioffe OB. Cloacal dysgenesis sequence: observations in four patients including three fetus of the second trimester gestation. Pediatr Dev Pathol 1998;1:281-288.
11. Carroll SG, Hyett J, Eustace D et.al. Evolution of sonographic findings in afetus with agenesis of the urethra, vagina and rectum. Prenat Diagn 1996;16:931-933.
12. Tank ES, Linderaner SM: Principles of management of exstrophy of the cloaca. Am J Surg 119.95,1970.
13. Jeffs RD: Exstrophy, epispadias, and cloacal and urogenital sinus abnormalities. Ped Clin North Am 34:1233-57,1987.
14. Loder RT, Dayiogler MM: Association of congenital vertebral malformations with bladder and cloacal exstrophy. J Pediatr Ortho 12:38993,1990.
15. Meglin AJ; Balotin RJ; Jelinek JS et al.: Cloacal exstrophy: radiologic findings in 13 patients. AJR 1990, 155:1267-72
16. Kutzner DK, Wilson WG, Hogge WA: OEIS complex (cloacal exstrophy): prenatal diagnosis in the second trimester. Prenat-Diagn. 1988, 8:247-53
17. Shalev E, Feldman E, Weiner E et al.: Prenatal sonographic appearance of persistent cloaca. Acta Obstet Gynecol Scand. 1986, 65: 517-8
18. Lande-IM; Hamilton-EF: The antenatal sonographic visualization of cloacal dysgenesis. J Ultrasound Med. 1986, 5: 275-8
19. Meizner I, Bar Ziv J: Prenatal ultrasonic diagnosis of cloacal exstrophy. Am J Obstet Gynecol. 1985, 153: 802-3