Background <p>Deep vein thrombosis (DVT) remains a major postoperative complication despite routine prophylaxis. This audit investigated an unexpected rise in DVT incidence in a tertiary surgical ward in Cairo, Egypt.</p> Methods <p>A six-month retrospective audit (December 2024–June 2025) included 212 adult patients undergoing general surgical procedures. All received enoxaparin prophylaxis. Clinically suspected DVTs were identified using Wells Score criteria and confirmed by duplex Doppler ultrasonography. Cold chain integrity of enoxaparin storage was reviewed in collaboration with pharmacy and biomedical engineering teams. Descriptive and comparative analyses were performed.</p> Results <p>Eighteen patients (8.5%) were clinically suspected to have DVT within 30 days postoperatively; 14 cases (6.6%) were confirmed by Doppler. Nine occurred during index admission and five during follow-up. Eleven of 14 confirmed cases (78.6%) were temporally linked to a malfunctioning ward refrigerator with storage temperatures exceeding 25&#xa0;°C. Patients with DVT were more likely to have undergone emergency surgery and less likely to have received mechanical prophylaxis, although these differences were not statistically significant. No major bleeding events were systematically recorded. Patients with DVT were more likely to have undergone emergency surgery and less likely to have received mechanical prophylaxis, although these differences were not statistically significant. By contrast, exposure to enoxaparin from the malfunctioning refrigerator was significantly associated with postoperative DVT (<i>p</i> = 0.002).</p> Conclusion <p>Cold chain failure was strongly associated with prophylaxis failure and is the most plausible contributor, though definitive pharmacological degradation was not confirmed. Infrastructure monitoring and mechanical prophylaxis adherence are essential to effective thromboprophylaxis. A prospective re-audit is scheduled following corrective measures.</p>