Establishing the normal ranges of female and male anal canal and rectal wall vascularity with color Doppler anorectal ultrasonography

MTN-033: a Phase 1 Study Comparing Applicator versus "as Lubricant" Delivery of Rectal Dapivirine Gel

Data to inform behaviorally congruent delivery of rectal microbicides as lubricants are scant. Dapivirine (DPV) is a nonnucleoside reverse transcriptase inhibitor which has been demonstrated to be well-tolerated and efficacious in multiple clinical trials when used in a vaginal ring formulation. DPV gel administered rectally with an applicator was found to be well-tolerated in a phase 1 clinical trial. MTN-033, a single site, open label, sequence randomized, crossover study, enrolled HIV-negative men to receive 0.05% DPV gel intrarectally using an applicator (2.5 g) and self-administered on an artificial phallus as lubricant (up to 10 g). The study evaluated the pharmacokinetics (in plasma, rectal fluid, and mucosal rectal tissue), safety, acceptability, and pharmacodynamics of DPV gel when applied rectally. Statistical comparisons between methods of application were performed using mixed effects models or Wilcoxon's signed rank tests. Sixteen participants used DPV gel by applicator and 15/16 participants used gel as lubricant (mean, 1.8 g; SD, 0.8). DPV plasma AUC0-24h after use as lubricant was estimated to be 0.41 times the AUC0-24h (95% CI 0.24, 0.88) after use with applicator. While DPV was quantifiable in plasma and luminal fluid, it was not quantifiable in tissue for both applicator and as lubricant administration. No related adverse events (AE) were reported, and 15/15 participants felt the gel was easy to use. Evidence of local delivery and systemic absorption of DPV when dosed as an anal lubricant supports the feasibility and potential for development of lubricant-delivered rectal microbicides. There were no safety concerns associated with use of DPV gel and participants reported finding it easy to use. However, lower DPV exposure in plasma and lack of quantifiable DPV in rectal tissue indicate that higher potency, concentration, and longer half-life antiretrovirals with optimized formulations will be needed to achieve protective tissue concentrations.

Can the Vaginal Photoplethysmograph and Its Associated Methodology Be Used to Assess Anal Vasocongestion in Women and Men?

Forty years ago, researchers documented changes in vascular and muscular activity within the anal canal of women and men who engaged in sexual self-stimulation. Vascular changes were assessed using a photoplethysmograph that aimed to detect changes in pelvic vasocongestion. An important advantage of detecting sexual response within the anal canal is that the device, its anatomical placement, and the data output are identical for women and men, therefore facilitating gender comparisons of response patterns. In this study, the vaginal photoplethysmograph (VPP), the most common measure of genital response in women, was administered intra-anally as an anal photoplethysmograph (APG) to examine its validity and sensitivity as an indicator of sexual response. The final sample comprised 20 women and 20 men who were exposed to 12, 90-s sexual and nonsexual film clips while their APG responses were recorded. Participants also rated their sexual arousal and affective responses to the stimuli. There was evidence that APG responses were specific to sexual stimuli and were sensitive to erotic intensity in women. The degree of discrimination between sexual and nonsexual stimuli was lower in men. Unlike most sexual psychophysiological studies, the positive correlation between physiological and self-reported sexual arousal was stronger in women than in men. There was a relatively high number of data artifacts and the waveform morphology was uncharacteristic of that typically observed with VPP. The potential role of anal musculature interference on the APG signal is discussed, as well as avenues for future research.

Preoperative rectal tumor embolization as an adjunctive tool for bloodless abdominoperineal excision: A case report

BACKGROUND

Abdominoperineal excision (APE)-related hemorrhage can be challenging due to difficult access to pelvic organs and the risk of massive blood loss. The objective of the present study was to demonstrate the use of preoperative embolization (PE) as a strategy for blood preservation in a patient with a large low rectal tumor with a high risk of bleeding, scheduled for APE.

CASE SUMMARY

A 56-year-old man presented to our institution with a one-year history of anal bleeding and rectal tenesmus. The patient was diagnosed with bulky adenocarcinoma limited to the rectum. As the patient refused any clinical treatment, surgery without previous neoadjuvant chemoradiation was indicated. The patient underwent a tumor embolization procedure, two days before surgery performed via the right common femoral artery. The tumor was successfully devascularized and no major bleeding was noted during APE. Postoperative recovery was uneventful and a one-year follow-up showed no signs of recurrence.

CONCLUSION

Therapeutic tumor embolization may play a role in bloodless surgeries and increase surgical and oncologic prognoses. We describe a patient with a bulky low rectal tumor who successfully underwent preoperative embolization and bloodless abdominoperineal resection.