N. J. McC. Mortensen

An analysis of rectal morphology in obstructed defaecation

Obstructed defaecation in the descending perineum syndrome has been attributed to anterior mucosal prolapse. Manometric and radiological measurements together with evacuation proctograms in 49 patients with obstructed defaecation and normal whole gut transit times were carried out and compared in a total of 25 controls. Proctography delineated four groups: (I) puborectalis accentuation,n=11; (II) rectal intussusception,n=25; (III) anterior rectal wall prolapse,n=11; (IV) rectocele,n=2. The anorectal angle at rest, maximum basal sphincter pressures and the rectoanal inhibitory reflex did not differ between the groups and controls. Group III achieved a greater increase in anorectal angle on straining than controls. Groups II and III exhibited significant perineal descent below the pubococcygeal line whereas group I did not. In perineal descent intussusception was the commonest morphological abnormality associated with obstructed defaecation. Isolated anterior mucosal prolapse was not observed, making local treatment aimed at reducing its bulk questionable.

Endorectal sonography: laboratory and clinical experience in Bristol

The normal echographic pattern produced by the colon and rectum has been investigated in vitro. Five basic ultrasonic layers or interfaces have clearly been identified; a first echogenic layer produced by the mucosa, then an echopoor layer representing the mucosa and muscularis mucosae, an echogenic layer which was submucosa, echopoor layer which was muscularis propria and an echogenic layer which was either pararectal fat or serosa.The effectiveness of endoluminal ultrasound (ELU) in the pre-operative staging of rectal cancer has been assessed in a group of 67 patients who were also, where possible, graded by digital examination and in some cases computer aided tomography (CT) (33 patients). Digital examination had an overall accuracy of 50% and could predict invasion beyond or confinement to the rectal with an accuracy of 64%. ELU is a highly accurate method for staging local invasion and when compared to post-operative histopathology had an overall correlation coefficient of 0.88 (p< 0.001) (Rank Spearman). Our overall accuracy was 91 % and it could predict invasion beyond the muscularis propria with a sensitivity of 96%, specificity of 94% and positive predictive value of 98%.In the cohort studied by both radiological techniques ELU was more accurate than CT where overall accuracy was 79%, sensitivity was 84%, specificity was 63% and the positive predictive value was 88%.

The relationship between perineal descent and denervation of the puborectalis in continent patients

It has been suggested that perineal descent causes puborectalis neuropathy. To elucidate this, perineal descent was measured on standard proctograms and prolongation of mean motor unit potential duration was used as the index of denervation of the external sphincter and puborectalis in 9 male and 18 female patients with perineal descent and obstructed defaecation. The findings were compared with 21 normal controls. There was no significant perineal descent below the pubococcygeal line at rest but both males and females had abnormal descent of the anorectal angle on straining and a similar degree of external sphincter neuropathy. Females, however, exhibited a significant degree of puborectalis denervation compared with controls (p<0.001) and with male patients (p<0.001). Thus external sphincter denervation was associated with perineal descent in both sexes whereas other causes, of which obstetric trauma is a possibility, must be implicated in the puborectalis neuropathy of the females studied.

Endosonography of the rectum

The following papers were presented at the first daylong symposium ever held on the subject of endosonography of the gastrointestinal tract which took place in Homburg/Saar , FRG, on 26th June 1986. During the morning there were papers on the theoretical physics of endosonography and on upper gastrointestinal endosonography. In the afternoon the subject was rectal endosonography covering technical aspects, clinical results and comparison with other techniques of local tumour staging.