# Postoperative Complications > Postoperative complications for BDS General Surgery — the fever timeline wind to wonder drug, wound dehiscence, secondary haemorrhage and DVT prevention. - Canonical URL: https://prepelephant.com/topics/bds/general-surgery/postoperative-complications-bds - Exam / course: BDS · Subject: General Surgery - Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team - First published: 2026-10-02 - Last updated: 2026-10-02 - How to cite: "Postoperative Complications", PrepElephant, https://prepelephant.com/topics/bds/general-surgery/postoperative-complications-bds ## Direct answer Fever on the first postoperative night has a far shorter differential than fever on day five — the timeline is the diagnostic instrument. The classical mnemonic runs wind, water, wound, walk, wonder drug: atelectasis in the first 48 hours (still the commonest early cause), urinary tract infection around days 3-5, wound infection classically from day 5, deep vein thrombosis and pulmonary embolism in the second week, and drug fever at any time. Beyond fever, complications divide by clock: immediate (airway obstruction, primary haemorrhage, aspiration), early (paralytic ileus, urinary retention, wound problems), and late (secondary haemorrhage around day 7-10 from infection eroding a vessel, incisional hernia, adhesions). The preventives are unglamorous and proven — early mobilisation, breathing exercises, adequate analgesia, hydration, thromboprophylaxis — and the two wound catastrophes worth reciting are dehiscence on day 5-7 (the pink trickle that precedes burst abdomen) and surgical site infection needing open-and-drain. ## What you must remember - **The fever sequence with days:** wind — atelectasis day 1-2; water — urinary infection day 3-5 (change the catheter, send urine culture); wound — surgical site infection day 5-7; walk — deep vein thrombosis and pulmonary embolism day 5-14; wonder drug — drug fever any time; plus fifth-day appendicitis-bundle? no — add subphrenic and pelvic abscess when fever returns after day 7. - **Wound dehiscence and burst abdomen:** dehiscence typically day 5-7, announced by a pink serosanguinous discharge through the suture line — if deep, the classical event is abdominal contents extruding (burst abdomen), an emergency covered with sterile saline-soaked towels and taken to theatre for resuscitation and re-suture with retention sutures; risk factors are cough, distension, obesity, steroids, hypoproteinaemia, malignancy and infection. - **Haemorrhage by clock:** primary (during operation), reactionary (within the first 24 hours as pressure and vasoconstriction wear off — slipping ligature), secondary (day 7-14, eroded by infection, the dental post-extraction bleed of the second week); management of shock first, then the source. - **Venous thromboembolism:** Virchow's triad of stasis, endothelial injury and hypercoagulability; calf pain and swelling, Homans sign unreliable but classical; diagnosis by doppler ultrasound, treatment with therapeutic anticoagulation; prophylaxis by early mobilisation, graduated compression and low molecular weight heparin for risk-stratified patients. - **Chest complications:** atelectasis from shallow breathing and retained secretions — fever, tachypnoea, basal crackles; treated and prevented by incentive spirometry, deep breathing, coughing, mobilisation and analgesia good enough to cough with. - **Paralytic ileus and urinary retention:** obstipation and absent bowel sounds after abdominal surgery, managed by nil orally, nasogastric decompression and fluid-electrolyte correction; retention common after pelvic surgery and anaesthesia, relieved by catheterisation. - **Surgical site infection:** warmth, tenderness, induration, discharge — open the wound, culture the pus, pack for secondary intention; antibiotics only for spreading cellulitis or systemic signs. ## Reading a temperature chart like a story A chart tells more than any list. Day 1, 38 °C, coarse basal crackles, patient splinting on coughing: atelectasis — chest physiotherapy, spirometry, analgesia; it settles. Day 6, fever returns, the wound is tender and hot with a fluctuant centre: surgical site infection — remove alternate sutures, open, culture, pack. Day 9, fever with a rising drain output of old blood and later a bleed from the wound: secondary haemorrhage — resuscitate, explore, and expect an infected vessel stump. Day 12, a swollen tender calf after a long immobile recovery: deep vein thrombosis — doppler, anticoagulate, and ask why prophylaxis failed. None of these events is exotic; each is the predicted behaviour of a body that has been cut, dried, starved and kept in bed. The counter-curriculum is the enhanced-recovery logic — get the patient drinking, walking and breathing on day 1 — because mobilisation simultaneously prevents atelectasis, ileus, retention and thrombosis: one intervention, four complications down. ## How the exam frames it The classical long question is "describe the causes of postoperative fever in chronological order" — the mnemonic earns its marks, but the examiner wants the matching day-ranges and one investigation per cause (spirometry findings, urine culture, wound culture, doppler). The second favourite is wound dehiscence — definition, day of onset, the pink-discharge warning, risk factors and management. MCQs mine the numbers (day 5 wound infection, day 7-10 secondary haemorrhage) and the differences between primary, reactionary and secondary bleeding. Indian viva settings add the practical dental question: post-extraction bleeding and swelling after going home — the expected answer pairs local measures (pressure, pack, sutures) with systemic screening, and reminds the examiner that most "complications" in dental practice are local, preventable and time-linked. ## Frequently asked questions ### What is the most common cause of fever in the first 48 hours after surgery? Atelectasis — alveolar collapse behind shallow breathing and retained secretions — managed with deep-breathing exercises, incentive spirometry, coughing and adequate analgesia. ### How does secondary haemorrhage differ from reactionary haemorrhage? Reactionary bleeding occurs within 24 hours as vasoconstriction and pressure ease (classically a slipping ligature); secondary bleeding occurs around days 7-14 from bacterial erosion of a vessel and signals infection. ### What heralds abdominal wound dehiscence? A pink or serosanguinous discharge through the suture line around day 5-7, often after coughing — the warning before frank burst abdomen with evisceration. ### How is postoperative deep vein thrombosis prevented? Early mobilisation, graduated compression stockings, adequate hydration, and risk-stratified low molecular weight heparin for high-risk patients — the practical answer to Virchow's triad. ### When is a surgical site infection suspected and what is the first step? When the wound becomes painful, warm, indurated or discharges, typically from day 5 — the first step is opening the wound and draining pus for culture, not simply starting antibiotics.