Complications associated with laparoscopic ovariectomy in mares

Abstract

Laparoscopic ovariectomy has become widely accepted as the gold standard approach for removal of both neoplastic and non-neoplastic ovaries in the mare (Lloyd et al. 2007). In the vast majority of hospitals such an approach is typically made to the standing patient as, when standing, the ovaries are positioned very conveniently for flank removal under endoscopic control. Preoperative food deprivation for 24–48 h is usually advised to facilitate the procedure. Once a surgeon has become familiar with the technique, it is relatively straightforward with few major complications. Well recognised complications include difficulty in performing the procedure because of inadequate preoperative food deprivation, poor intra-abdominal visualisation as a consequence of retroperitoneal carbon dioxide accumulation during abdominal insufflation or because of peritoneal detachment (these can be avoided by using a screw-in cannula or simply by ensuring that insufflation is intra-peritoneal) or because of accumulation of intra-abdominal fluid or blood; this last complication is rarely encountered except in horses with abdominal neoplasia or peritonitis. Inadvertent penetration of the caecal base during right flank laparoscopy, or of the spleen during a left flank approach, can usually be avoided by thorough preoperative evaluation of the abdomen, insufflation of the abdomen with carbon dioxide prior to insertion of the cannula, insertion of the cannula under direct endoscopic control or by having an assistant place an arm per rectum during insertion of the first cannula (subsequent portals can be created under direct endoscopic control). Difficulties in restraining the patient whilst maintaining it in the standing position can make the procedure awkward or even impossible. Whilst this may be the result of the mare’s temperament, over-inflation of the peritoneal cavity with carbon dioxide is undoubtedly painful and experience generally encourages surgeons to rely on less distension. Whatever the situation, achieving the correct level of sedation is absolutely critical; a variety of agents, including a2 antagonists and opioids, are used typically in combination. If the level of sedation is inadequate, the patient becomes restless and may not tolerate the procedure; however, if too profound, patient ataxia can prove equally problematic. Determining an effective method of patient restraint is absolutely fundamental to successful laparoscopic surgery. Intraoperative complications directly associated with ovariectomy, include inadequate haemostasis during section of the ovarian pedicle and inadvertent injury to the adjacent uterine horn, possible when trying to dissect very large granulosa thecal cell tumours that may lie close to or even become attached to a uterine horn. Haemostasis has become much easier with the advent of affordable electrical vessel sealing devices (Hubert et al. 2006; Lloyd et al. 2007). We have not encountered a case in which haemorrhage from the ovarian pedicle could not be controlled by these means. Removal of large ovaries from the peritoneal cavity can present a problem. In mares with a unilocular fluid-filled ovary, this is seldom difficult because intra-abdominal drainage will reduce ovarian size and facilitate retrieval. However, for more solid ovaries, one option is to cut the enlarged ovary into pieces and remove them piecemeal. Dropping ovaries into a proprietary laparoscopic tissue retrieval bag is often difficult because of the size of pathological equine ovaries. A sterilised plastic bag may also be used to accommodate larger ovaries and can facilitate their removal from the abdomen. A well recognised intraoperative complication is moderate haemorrhage from the abdominal wall when creating a large portal for ovarian removal. This is usually avoidable by careful dissection of the abdominal musculature. Some surgeons prefer to remove both ovaries (in bilateral cases) through one major flank incision, which requires transfer of one ovary across the abdomen. In the paper published in this issue by Madron et al. (2012), the breakage and subsequent loss of the working end of a laparoscopic claw forceps and its subsequent successful retrieval aided by use of a rumen magnet, are described. This is not a complication so far encountered in Corresponding author email: tim.greet@rossdales.com bs_bs_banner