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

5. • 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.

6. • 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.

7. • 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)

8. 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 .

9. • 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.

10. Superior pubic
ramus
Inferior ramus

13. • 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.

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

16. • 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.

18. 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.

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

20. • 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.

21. • 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.

24. Common causes for erroneous interpretation of prone, cross-table lateral x-ray
include:
1. 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.

25. 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.

26. 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.

27. • 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

28. Wingspread conference classification
(1984)

29. PENA CLASSIFICATION (1995)

30. Krickenbeck classification for ARMs
(2005)

31. Comparison

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

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

34. 1- Perineum , 2- Vestibule

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

44. • 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.

47. 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.

49. 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

50. 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

51. • 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

56. THANKS