Invertogram ANORECTAL MALFORMATION ( ARM ) PRANAYA

ANORECTAL MALFORMATION ( ARM ) INVERTOGRAM DR. PRANAYA

1. INVERSION RADIOGRAPHY

2. Invertography was first described by Wangensteen and Rice in 1930. Stephens described PC line by dissection of 25 stillborn pelvis in documenting the attachment of the levator ani to the pelvic wall both macroscopically and radiologically , with opaque wires marking the attachment of the levator ani

3. Technique Six to eight hours after the birth, a newborn baby with ARM should be held upside down for at least 3 minutes strict lateral view (in this upside down position) is taken with the thighs of the baby flexed at hip, and beam accurately centered on the greater trochanter . Anal dimple and the natal cleft should be outlined by barium paste , Coin, metal pointer

4. In a correctly taken radiograph: ( i ) both the ischial bones would accurately superimpose (ii) the terminal blind bowel will be rounded and well-distended. Interpretation of an invertogram should be attempted only, if both these features are present otherwise it may be fallacious.

5. During the reading of an invertogram , besides evaluating the level of bowel gas 1. Spine- Congenital anomalies of the spine are common. 2. Presence of gas in the region of urinary bladder and vagina, which would indicate an underlying fistula.

6. Basic purpose of invertography is to identify the relationship of the gas bubble in the blind pouch to the bony pelvis, which in turn indicates the relation to the levator ani muscle complex. By using three lines, a concept which was first put forward by Stephens and Smith (1971)

7. THE THREE LINES ARE: ( i ) PC( pubococcygeal ) line (ii) the I ( ischial ) line or I point (iii) the anal pit line . A gas bubble situated above the PC line is designated “high” anomaly. one located between the PC and I line or point “Intermediate” anomaly. if it extends below the I line (point), then it is called “low” anomaly .

8. PC line stretches from the upper border of the symphysis pubis to the sacrococcygeal junction. At the symphyseal end this line is taken as the center of the “boomerang” shape of the os pubis, which corresponds with the upper border of the symphysis . The top of the “boomerang” corresponds with the superior pubic ramus . Ossification of the pubis begins in the second fetal month and extends along the superior pubic ramus medially to the body.

9. Superior pubic ramus Inferior ramus

10. The ischial line (I line) and I point are related to the ossification center of the ischium , which is a comma shape in the neonate. The I point is demarcated on the x-rays at the inferior end of the ischial comma. The I line is drawn through the I point parallel to the PC line and corresponds to the upper surface of the bulb of the urethra in the male and the upper limit of perineal body and the level of the triangular ligament in the female. The anal pit is normally 1–2 cm caudal to the ossified ischium .

11. Bladder Neck, Verumontanum , Pelvic Reflection From Rectum To Prostate, External Os Of The Cervix

12. Cremin (1971) did not find PC line very accurate. They proposed a “M line” or “M point”, which is located at the junction of upper two-third and lower one-third of the ischium . Anomalies are then divided into “high” and “low” types with no intermediate category.

13. Potential Pitfalls Of This Technique In Order To Avoid Misdiagnosis. 1. Insufficient time for the gas to reach the terminal bowel. 2. Meconium blocking the terminal segment. 3. In a crying child, puborectalis sling may move significantly up or down giving erroneous results. 4. Gas may escape through a fistula. 5. Improper technique—in positioning, centering or marker placement.

14. NEWER MODIFICATIONS 1. Prone cross table lateral view ( Narasimharao et al, 1983). 2. CT invertography (Leighton and de Campo, 1989 )

15. An upside-down inversion x-ray is no longer performed, having been replaced by a prone, cross-table lateral examination of the pelvis, with the hips elevated over a bolster . The prone cross-lateral view’ has few advantages like the baby is comfortable, whereas in invertogram requires splints and adhesive tapes and the baby keeps crying due to which puborectalis sling contracts and hence there is deceptive obliteration of the lower rectum.

16. The prone, cross-table lateral x-ray should be delayed for 12–24 h after birth to allow gas to reach the distal rectum. The baby should be placed in the genupectoral position for 3 min before taking the film to allow gas to displace meconium and rise to the termination of the pouch. Barium paste or contrast-soaked gauze placed in the natal cleft is more accurate than a metal marker. A catheter may be placed in the urethra to make delineation of the urethra more obvious, although this is not essential. The greater trochanter should be marked with a marker pen on the upper thigh and the x-ray beam centered on this spot.

17. Common causes for erroneous interpretation of prone, cross-table lateral x-ray include: Insufficient time for gas to reach the terminal bowel. 2. Meconium plug in the terminal gut may produce an erroneously high shadow if the gas does not displace the meconium . 3. Active contraction of the levator ani /sphincter muscle complex can push the gas shadow higher. 4. Gas escape through A fistula may confuse the xray . 5. Distortion by x-ray magnification resulting in the appearance of A longer gap between the gas within the terminal colon and skin. 6. Inappropriate placement of an anal marker may cause an error of assessment of the exact site of the anus on the skin. 7. Erroneous estimation of level of the lesion inside the sphincter muscle complex may occur if the pelvic floor muscles are relaxed, or if there is A sacral anomaly. 8. Gas in the vagina may be mistaken for gas in the distal bowel.

18. Ultrasonic examination Ultrasonographic examination has been used to know the pouch perineal distance. It can be performed through a transperineal or infracoccygeal route. Infracoccygeal route can directly demonstrate the puborectalis as a hypoechoic U-shaped band. The noninvasive nature and no radiation exposure are the main advantages, but it is highly observer dependent.

19. Computer tomography and magnetic resonance imaging Computer tomography (CT) and magnetic resonance imaging (MRI) of pelvis have been utilized for the direct visualization of the sphincteric muscles. These have been used for the structural evaluation of pelvic floor muscle and relation to the pouch, for both the pre- and post-operative evaluation. The exact location of fistula and relation to the pelvic floor muscle provides crucial information regarding the approach, whether a sagittal approach or an approach through abdominal route is required.

20. MRI and CT can be utilized for the assessment of structural development following different procedures for ARM MRI is considered superior to CT scan -- excellent soft tissue characterization, multiplanar imaging, and lack of ionizing radiation

21. Wingspread conference classification (1984)

22. PENA CLASSIFICATION (1995)

23. Krickenbeck classification for ARMs (2005)

24. Comparison

25. External anocutaneous opening at scrotum (1), perineum (2,3)

26. Fistula At --> 1- Base Of Penis, 2- Bulbar, 3- Prostatic, 4- Vesical

27. 1- Perineum , 2- Vestibule

28. Common Cloaca Canal ---- 1- Short , 2- Long

29. A three-day-old female child was admitted with a history of not passing meconium since birth. On examination, abdomen was distended. Careful examination revealed normally placed anal opening, with normal fourchette and small fistulous opening in the lower third of left labia majora . There was no meconium or any type of discharge from the opening. The anal opening was calibrated with number 8 infant feeding tube and a resistance was observed at about 2 cm from the anal opening. X-Ray ( invertogram along with feeding tube in situ ) was suggestive of membranous rectal atresia . The membrane was perforated blindly by using Hegar's dilator following which meconium was coming from the fistulous opening. Fistulogram revealed fistula between upper anal canal and the labia.

30. Journal of Minimal Access Surgery, Vol. 6, No. 4, October-December, 2010, pp. 114-115 A 3-day-old female child, (full-term, normal delivery) weighing 2.75 kg at birth with stable vitals, moderate abdominal distension and history of not being able to pass meconium was referred to us. Examination showed normal anal opening but red rubber catheter could not be passed beyond 3 cm of anal verge. Spine and external genitalia were normal. X-ray ( invertogram with red rubber catheter passed through anal opening) showed catheter abutting the air column in the bowel) An endoscopy was done with a 7.5F cystoscope . About 3 cm from the anal verge, the anal canal ended blindly and a membrane was visualized at the blind end. We incised the outer mucosal membrane, i.e. of the distal pouch with a bugbee , but the vision was lost due to technical reasons. Then anal retractors were used, and after the incision on the mucosa of the distal pouch, the inner mucosal membrane was seen bulging significantly due to meconium within it. Transanal membranotomy was done.

31. RECTAL-TAIL SIGN Invertogram in a case of ARM with intact bowel. Air-filled rectum is seen as a tail-like projection into the pelvic brim

32. Relationship of Sacral Development and Levator Muscle Development i . If sacrum is normal then muscle mass and innervation are also normal; ii. If S4, S5 are absent then muscle and innervation are usually still normal; iii. If S3–S5 are absent then there is variable degree of deficiency of the muscle mass, and patient is usually incontinent; iv. If S1–S5 are absent then muscles are markedly hypo-plastic, and all the patients are incontinent. Good indicator of development of the sacrum is by plain radiographs also but MRI IS GOLD STANDARD

33. A sacral defect, particularly hemisacrum , in association with imperforate anus and a presacral mass is known as the Currarino triad and has a strong familial tendency.. The sacral ratio is a valuable prognostic tool because it quantifies the degree of sacral hypodevelopment . Patients with ratios less than 0.4 are universally incontinent. Ratios that approach 1.0 usually predict a good prognosis

34. THANKS