Biliopancreatic diversion as described by Nicola Scopinaro
After BPD, the first phase of rapid weight loss occurs, lasting between several months to 1 year, mainly due to the reduced alimentary intake caused by the distal gastrectomy, and the post-feeding syndrome, owing to the interaction of the ingested material with the distal ileum. The long-term weight loss is then maintained by the malabsorptive effect of the Roux-en-Y limb.
24.2 Type and Incidence of Post-operative Complications
BPD is a safe operation, with low post-operative morbidity and mortality . Nevertheless, chronic malabsorption which is crucial for the therapeutic effects can be responsible for some negative side effects.
24.2.1 Protein Malnutrition
This condition represents the most severe side effect of BPD. Its patophysiology is linked to several aspects of the intevention: the gastric volume affects the amount of food, and then proteins that can be assumed, while the length of the alimentary limb conditions the amount of small bowel suitable for proteic absorbption. Moreover, after BPD, there is an increased loss of endogenous nitrogen [1, 6], requiring a higher intake of dietary proteins. Severe hypo-proteinemia may result, owing to an improper nutritional regime.
The incidence of protein malnutrition is higher in the first two years after the intervention, and reduces thereafter.
Guedea reported protein malnutrition in 10 % of 74 patients, who underwent BPD and who had a 5-year-follow-up . In a recent series of 287 patients with classical BPD, severe hypoproteinemia was observed in 1.7% of patients at year 1 .
According to Scopinaro, protein malnutrition can be reduced to 1 %, with a recurrence rate of 0.5 %, by correctly balancing the volume of the gastric pouch and the length of the alimentary limb in accordance with the patients’ alimentary habits and the desired EWL% .
24.2.2 Chronic Anaemia
Distal gastrectomy and the exclusion of the duodenum and proximal jejunum impair absorption of iron and folates, facilitating chronic anaemia. Whereas macrocytic anaemia, due to vitamin B12 deficiency, is rarely seen, if adequate supplementation is provided, iron-deficiency–related microcytic anaemia can be observed more frequently, namely in the presence of chronic bleeding. In particular, fertile women are at high risk of developing iron-deficiency anaemia after BPD. Guedea et al., in a 5-year follow-up study, showed post-operative anaemia in 59.5 % of fertile women; despite oral nutritional integrations . The incidence of iron-deficiency anaemia after BPD can be reduced to 5 % using adequate iron and folate integration .
24.2.3 Secondary Hyperparathyroidism
An association between morbid obesity and secondary hyperparathyroidism is well documented, as elevated levels of parathyroid hormone (PTH) and 1,25-OH vitamin D, together with reduced levels of 25-OH Vitamin D, have been observed in up to 50 % of patients before the operation . Hamoui observed a correlation between PTH levels and BMI in obese patients . After BPD, altered absorption of calcium can be responsible for hypo-calcemia and further elevation of PTH levels, even after appropriate supplementation of vitamin D . As a consequence, increased bone reabsorption, bone demineralization, osteoporosis and osteomalacia may occur . Scopinaro showed histopathological bone demineralization in one third of patients after BPD, mainly during the first 4 years post-operatively .
High post-operative levels of markers of bone turnover, and decreased bone-density were observed 1 year after BPD (a peculiar variant), irrespective of high doses of calcium integration, and in the absence of secondary hyperparathyroidism.
Decreased bone mass was considered an adaptive phenomenon of the skeleton, secondary to decreased mechanical load after bariatric surgery .
After BPD with duodenal switch, in a 10-year-follow-up study, Marceau observed bone fractures in 17 % of patients with classic BPD . However, recent studies seem to exclude an increased risk of bone demineralization, osteoporosis and bone fracture after bariatric surgery, in comparison with a healthy population [15, 16], thus leaving some uncertainty concerning the clinical significance of secondary hyperparathyroidism and calcium metabolism after BPD.
24.2.4 Proctologic Sequelae
Altered composition of faeces (lower pH in comparison to healthy people), together with increased frequency of bowel movements per day after BPD, account for the occurrence in some patients of proctologic disorders, such as anal fissure, prolapsing haemorrhoids, perianal abscesses and fistulas.
After the implementation of adaptive mechanisms, the incidences of these conditions tend to decrease over time. Nevertheless, their persistence may severely impair the QoL and, together with the “foul smell” of stools, which is characteristic of subjects with BPD, may significantly affect the patient’s social life.
24.3 Indications to Surgical Revision
A variable rate of surgical revisions has been required in the long term after BPD. Surgical revision may include remodelling of the length of the bowel limb, bowel continuity restoration or surgical revisions of the gastro-enteric-anastomosis (GEA). In addition to GEA revision, due to stenosis or marginal peptic ulcers, bowel remodelling is sometimes required to treat side effects of chronic malabsorption, insufficient weight loss or weight regain, whereas restoration of the small bowel continuity can be the final option for severe relapsing protein malnutrition. In the experience of Scopinaro, 6.3 % of patients required surgical revision after a 19-year-follow-up , whereas in a series comparing BPD with duodenal switch, Marceau reported that 18.5 % of 248 BPD patients had surgical revision during a 10-year-follow-up study . However, the need to restore the continuity of the small bowel was comparable in the two series (2 % and 2.7 %, respectively).
Relapsing protein malnutrition is the most frequent reason for surgical revision. The first step of the treatment must aim at restoring an adequate nutritional status before surgery, usually using parenteral nutrition.
For a proper planning of surgery, a thorough clinical and nutritional evaluation must be used to detect whether chronic malabsorption is attributable to insufficient intestinal absorption of proteins or to insufficient nutritional intake. On a clinical basis, the presence of diarrhoea and the overall food intake must be evaluated.
Diarrhoea usually means a reduced tolerance towards the malabsorptive component of the BPD.
In this case, in the presence of adequate daily food intake, elongation of the common channel at the expense of the biliary limb could be the treatment of choice.
In the absence of diarrhoea, elongation of the alimentary channel, moving the common channel proximally along the biliary limb, can provide a longer ileal tract improving protein absorption, without affecting the fat-related malabsorption. In the absence of adequate oral nutrition, the restoration of the small bowel continuity should be considered.
Among the other side effects of chronic malabsorption, proctologic sequelae and chronic diarrhoea, in addition to “foul-smelling” stools, these can be improved by an elongation of the common channel, moving proximally the biliary limb along the alimentary one. In this case, possible weight regain must be anticipated.
Other conditions, such as iron-deficiency anaemia and hyperparathyroidism, as well as micronutrient imbalances, should be evaluated from a wider perspective, together with protein asset, desired %EWL and diarrhoea, in order to personalize surgical re-intervention as a “tailor’s suite”.
Insufficient weight loss: BPD is an extremely effective procedure, affording an excellent EWL% in the vast majority of patients. Nevertheless, suboptimal compliance to dietary recommendations and lifestyle modifications may significantly reduce the effectiveness of the procedure, thus preventing satisfactory results.
Moreover, in spite of an overall EWL% higher than 50 %, some patients may display a BMI which is still in the obesity range (i.e. >30). These results should be evaluated on an individual basis, considering on the one hand the overall QoL, the presence of significant side effects of chronic malabsorption and the way the patients are able to cope with them, and, on the other, the patient’s compliance to post-operative integration and nutritional advices.
Weight regain: Excessive adaptive phenomena after BPD may account for a significant long-term weight regain, but this is still open to question. Conversely, an increased dietary intake of alcohol and carbohydrates, such as mono and disaccharides – which can still be absorbed along the alimentary limb – determines an increase of both energy intake and overall weight. If this is the case, the proper management should be nutritional advice, as no surgical revision could conveniently cope with a wrong alimentary regime.
If weight regain occurs, but no wrong alimentary habit can be documented, and no significant side effect of chronic malabsorption is clinically evident, the shortening of the common channel to increase malabsorption could be the correct solution. Conversely, the possibility of reducing the gastric pouch, in order to increase the restrictive component, requires a word of caution, because of the risk of insufficient protein intake.
24.4 Physiopathological Basis of Limb Remodelling in BPD
Proteins and starch can be reabsorbed along the whole length of the alimentary limb, from the gastro-enteric-anastomosis to the ileo-cecal valve. Moreover, the cecum and ascending colon, because of intestinal adaptive phenomena, become an additional site of protein absorption. Simple sugars and alcohol can be reabsorbed along the whole alimentary limb as well. The short common channel remains the only site for effective reabsorption of fatty acids and bile salts, thus significantly reducing the total amount of energy absorbed from food.
These aspects must be thoroughly considered to explain the clinical results of BPD, and its adverse effects. However, they are of crucial importance in cases of surgical revision.
Varying the length of the common channel at the expense of the alimentary limb affects fat and energy absorption, without directly affecting starch and proteins.
Shortening the common channel below 50 cm or elongating it along the alimentary limb determines a consensual variation in the threshold of fat and energy absorption. Accordingly, relative effects on steatorrhea, diarrhoea and “foul-smelling” stools can be expected.
Elongating the common channel at the expense of the biliopancreatic limb determines increased absorption of macronutrients and energy, as a result of the elongation of the entire alimentary circuit.
Elongating the alimentary limb at the expense of the biliopancreatic limb improves the absorption of protein and starch, without modifying the amount of fat.
Before modifying the relative length of bowel limbs after BPD, the surgeon must take into account the effectiveness of the adaptive mechanisms that occur after the first operation. Moreover, the overall capacity to eat, that is greatly dependent on the total capacity of the gastric pouch, must be evaluated, concomitantly and in addition to the absorptive function of the alimentary circuit.
In other words, a proper strategy before redo surgery can be formulated only after an 18- to 24-month interval following BPD, when proper adaptive mechanisms have already occurred, and the eating capability has been restored completely.
24.5 Problems and Specific Aspects of Redo Bariatric Surgery
Approach: Although the laparoscopic approach can be chosen for a redo procedure even in case of previous open bariatric surgery , we prefer to perform a re-laparotomy when initial BPD had been performed using open surgery. In our opinion, further indications to open approach include the presence of a large incisional ventral hernia and the requirement for additional surgery other than cholecystectomy.